O-rings, military and aerospace specifications
Mil-spec O-rings by designator: MS28775, M83248, M25988 and the AS families
A mil-spec O-ring is ordered by a military or SAE aerospace part number that fixes both its size and the material document behind it: M83248/1-214, for example, names the family (M83248), the slash sheet or class (/1) and the AS568 dash size (-214). Most of the MIL documents behind these callouts are cancelled or inactive for new design and have SAE successors, so the index below gives the current document for each family, its polymer and durometer, and whether a qualified products list exists. Send the callout exactly as the print reads and we quote it supplied against that document, in the compound it calls for, with a certificate of conformance; when the print calls out a document with a qualified products list, the part comes from a manufacturer on that list.
Every family on this page but NAS1611 and NAS1612 shares one size system: the three-digit dash is the AS568 dash (the AS568 O-ring size chart carries every size), so MS28775-214, M83461/1-214 and M83248/1-214 are one size in three materials. Each of those family pages carries a designator-to-AS568 table with the inside diameter and cross-section for ten common dashes, and every dash links to its own size page. NAS1611 and NAS1612 are the exception: their AIA and DLA records give no AS568 size, so their page has no such table and we quote the part number as printed. The material behind a callout lives in a separate document (MIL-PRF-25732, AMS7276), and that document decides the polymer and the hardness class. Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
The families, their current documents and their pages
| Designator family | Current document | Superseded document(s) | Polymer and durometer | QPL |
|---|---|---|---|---|
| MS28775 | SAE-AS28775A (revised 2008, reaffirmed 2025) for the drawing; MIL-PRF-25732 rev E (2024) inactive for new design; SAE-AMS-P-25732A cancelled 2003 | MIL-P-25732 and MIL-PRF-25732 are the same document (prefix change); the MS28775 drawing was cancelled in 2000 and superseded by SAE-AS28775 | Nitrile (NBR); durometer by compound | Yes: QPL-25732, government (DLA QPD) |
| M83461/1 | SAE-AS83461/1C (reaffirmed 2021); material SAE-AMS-P-83461 (1998) | MIL-P-83461 and MIL-P-83461/1, cancelled 2003-10-01 | Nitrile (NBR); durometer by compound | None on record |
| M83248/1 and M83248/2 | SAE-AS3209C (AS3209 was named by the 2008 notice) and SAE-AS83248/1A on AMS7276 (Class 1); SAE-AS3581A and SAE-AS83248/2A on AMS7259 (Class 2) | MIL-R-83248 (cancelled 2001), /1 (2008), /2 (2004) | Fluorocarbon (FKM); 75 (/1), 90 (/2) | SAE non-government QPL on AMS7276 and AMS7259 |
| M83485/1 | SAE-AMS7287A (2022), the document Freudenberg's 2024 Aerospace Part and Material Cross-Reference lists | MIL-R-83485, cancelled 2002-10-23; SAE-AMS-R-83485A, cancelled 2014 | Fluorocarbon (FKM), low-temperature grade; durometer by compound | None on record |
| M25988/1, /2, /3 and /4 | MIL-DTL-25988/1 to /4, Active (2026-04-21); base MIL-DTL-25988 rev D inactive for new design (2025), in part superseded by SAE-AMS-R-25988, which SAE cancelled in 2017 (DoD withdrew its adoption 2018-01-02) and reissued as revision B in 2023 | MIL-R-25988 is the same document (prefix change) | Fluorosilicone (FVMQ); 70 (/1), Class 3 (/2), 60 (/3), 80 (/4) | Yes: QPL-25988, government (DLA QPD) |
| MS29513 and MS29512 | SAE-AS29513C and SAE-AS29512C (reaffirmed 2021); material SAE-AMS-P-5315C | MIL-P-5315, cancelled 2002-02-28 | Nitrile (NBR); durometer by compound | None on record |
| NAS1611 and NAS1612 | NAS1611 Rev 12 and NAS1612 Rev 8 (2014), NAS1613 Rev 6 (2012): AIA, Active; DoD adoption reaffirmed 2018 | none on record | Ethylene propylene (EPDM); durometer by compound | None on record (AIA keeps none for NAS parts) |
| AS3582 | SAE-AS3582 (reaffirmed 2018) on SAE-AMS3304J (2019) | MS9068 (legacy callout): status, ask with the quote | Silicone (VMQ); 65 to 75, the AMS3304 title class | Not stated |
| AS9386 and AS9385 | SAE-AS9386B (2021) on SAE-AMS7267H (2021); SAE-AS9385 cancelled 2020, DoD adoption withdrawn 2024 | MS9386 and MS9385, canceled 1999 and superseded by SAE-AS9386 and SAE-AS9385 | Silicone (VMQ); 70 to 80, the AMS7267 title class | Not stated |
| AS3209 and AS3208 | SAE-AS3209C and SAE-AS3208A (both stabilized) on SAE-AMS7276 (Active) | none (SAE size sheets) | Fluorocarbon (FKM); 70 to 80, the AMS7276 title class | SAE non-government QPL on AMS7276 |
The mil-spec chart gives each document's dated status and its successor or parallel document; the mil-spec cross-reference by dash lists the military and SAE part numbers at each AS568 dash; the O-rings hub lists every compound family we quote. Backup rings (MS28774, MS28782, MS27595 to AS8791) and X-rings have their own pages: backup rings, X-rings. Sheet and molded-shape callouts to MIL-R-6855 (now MIL-PRF-6855) are explained in the MIL-R-6855 guide.
| Callout | Size sheet | Material document | Polymer and hardness class | QPL |
|---|---|---|---|---|
| AS3581-XXX | SAE-AS3581A (stabilized 2020-05-12) | SAE-AMS7259, Active | FKM, 85 to 95 | SAE non-government QPL available |
| AS3085-XXX and AS3084-YY (boss) | SAE-AS3085A and SAE-AS3084A (stabilized 2012-06-06) | SAE-AMS7280 (cancelled 1992 at revision F) | FKM, 70 to 80 | not stated |
| AS3569-XXX | SAE-AS3569A (2021-08-09) | SAE-AMS7270M | NBR, 65 to 75 | not stated |
| AS3570-XXX | SAE-AS3570A (reaffirmed 2025-07-17) | SAE-AMS7274K | NBR, 65 to 75 | not stated |
| AS3551-XXX | SAE-AS3551A (2020-10-09) | SAE-AMS7272G | NBR, 65 to 75 | not stated |
| AS3578-XXX | SAE-AS3578 (reaffirmed 2018-08-23) | SAE-AMS7271K | NBR, 60 to 70 | not stated |
| AS28778-YY and MS28778-YY (boss gasket) | SAE-AS28778C (reaffirmed 2021-11-08) | SAE-AMS-P-5510B (stabilized 2023; DoD-adopted, Active) | NBR; 90 by industry convention, not stated in the document | not stated |
| AMS7257-XXX | no separate size sheet | SAE-AMS7257E (2014-09-05) | FFKM, 70 to 80 | not stated |
| MS28774, MS28782, MS27595 (backup rings) | see the backup ring page | SAE-AS8791D (reaffirmed 2025-07-16) | PTFE | not stated |
How to read a mil-spec O-ring callout
The family and the dash
Read a callout from left to right: the letters and digits before the dash name the specification family and, where present, its slash sheet; the digits after the dash are the AS568 size. M83248/1-214 is the M83248 family, slash sheet 1 (Class 1, 75 hardness), in the -214 size, which AS568 lists at 0.984 in inside diameter and 0.139 in cross-section. The dash is a catalog lookup and says nothing about the material. MS28775-214, M83461/1-214 and AS3209-214 are the same size in three different documents.
Slash sheets and classes
A slash sheet is a numbered supplement to the base document, and families use it differently. On M83248 the slash sheet is the hardness class: /1 is Class 1 at 75 and /2 is Class 2 at 90. On M25988 the four slash sheets are class and grade combinations of one fluorosilicone: /1 is Class 1 Grade 70, /2 is Class 3, /3 is Grade 60 and /4 is Class 1 Grade 80, as the DLA ASSIST titles print them. On M83461 the slash sheet is the size sheet: /1 covers the standard sizes and /2 the boss sizes.
Suffix letters
A trailing letter on a document number is a revision: AS28775A, AS29513C, AMS7276J. A trailing letter inside a part number can mean something else, so never read it as a revision. On NAS1611 and NAS1612 parts, one manufacturer's 2024 aerospace cross-reference builds the -A part in its NAS1613 Revision 6 compound and the unsuffixed part in its Revision 2 compound; neither the AIA nor the DLA record defines the suffix. In Conquest Seal part numbers a trailing letter identifies a compound, not a revision.
Boss sizes, the 9xx dashes
The 900 series of AS568 (dash numbers 901 through 932) covers the straight-thread tube-fitting boss seals, and their cross-section changes with the dash. Several families carry a separate boss designator with a two-digit dash: AS3208-YY and AS3084-YY map to AS568-9YY per Freudenberg's 2024 Aerospace Part and Material Cross-Reference (pages 3 and 4), and the DoD's MS29512 and MS9385 drawings give their -YY parts the AS568-9YY nominal size, with an inside-diameter tolerance tighter than AS568's from -07 up (DLA ASSIST, read 2026-09-27). The MIL-P-83461/2 boss sheet writes its parts with the three-digit AS568 dash, M83461/2-9YY (DLA ASSIST ident 71937, read 2026-10-04); Freudenberg also prints a two-digit form, M83461/2-YY. The standard-size designator in the same family carries the three-digit dash. If the print shows a two-digit dash on one of these families, it is a boss seal. NAS1612 is a boss standard too, but no record maps its part numbers to AS568, so send them as printed.
The SAE split: an AS number for the size, an AMS number for the compound
The old MIL system bundled the size sheet and the compound into one slash-sheet number, so a cancelled slash sheet leaves an SAE number for the compound and one for the sizes. For M83248/1 the compound is SAE-AMS7276; for the sizes, DoD cancelled M83248/1 in 2008 and pointed future purchases to SAE-AS3209 (boss sizes to AS3208), and SAE later issued AS83248/1 (2014), which DoD adopted on 2025-11-03. In the SAE system the AS document carries the sizes and its title names the AMS material document outright, so AS3209 is the size sheet and AMS7276 is the compound. A complete SAE callout therefore needs both numbers. When a print shows only the AS number, we quote the AMS material its title names.
One dash, every family: the cross-reference concept
M83485/1, AS3582 and AS9386 follow the same pattern: the designator plus the three-digit AS568 dash. 2-XXX dash numbers correspond with AS568, so a Parker® 2-214 is the -214 size; the material is a separate question answered by the compound number on the print.
To read one part number, type it into the O-ring cross-reference tool: it shows the AS568 size the dash names, the document and its DLA ASSIST / SAE Mobilus status, and the other part numbers at the same dash.
Each family page tabulates its part numbers at ten common dashes; each size page lists the mil-spec part numbers for its size: AS568-006, AS568-010, AS568-012, AS568-112, AS568-114, AS568-116, AS568-210, AS568-214, AS568-222, AS568-325.
What to send for a quote
Send the designator exactly as the print reads, including the slash sheet and any suffix letter, and the dash number. Add the quantity and the certification the order needs: a certificate of conformance to the document, lot traceability, and any first-article or test-report requirement your quality system imposes. If the print names a compound or a manufacturer, include it; if it names a revision, include that too. We reply with the part quoted in the compound the print names, supplied against the document, and we say so on the paperwork.
- Designator and dash as printed, for example M83248/1-214 or MS28775-214
- Slash sheet, class or grade where the family has one (M25988/3-028, M83461/2)
- Suffix letter where the print carries one, such as the -A on a NAS1611 part number
- Quantity, and whether it is a one-time buy or a repeating requirement
- Certification: certificate of conformance, lot traceability, cure date, test reports, first article
- The compound or manufacturer if the print or your approved source list names one
What a qualified products list is
A qualified products list names the manufacturers whose product has been tested and listed by the qualifying activity against a governing specification; a distributor is not on it, and Conquest Seal is not on any QPL. The government lists live in DLA's Qualified Products Database, searched by governing specification, and some SAE AMS documents carry a non-government QPL held by SAE.
Of the families on this page, MIL-PRF-25732 (MS28775) and MIL-DTL-25988 (M25988) carry government QPLs, QPL-25732 and QPL-25988. AMS7276 and AMS7259, the compounds behind M83248/1, M83248/2, AS3209 and AS3581, carry SAE non-government QPLs. The cancelled MIL documents (MIL-R-83248, MIL-P-83461, MIL-P-5315, MIL-R-83485) show no QPL on record, and NAS documents are published by the Aerospace Industries Association, which keeps no qualified products list for NAS parts. When the print calls out a document with a QPL, the part comes from a manufacturer on that list and the certification names it.
How to check a list before you order: what QPL-listed means for O-rings. Crossing a maker's part number to a mil-spec callout: O-ring part number cross-reference.
Frequently asked
How do I read a mil-spec O-ring callout like M83248/1-214 on a drawing?
M83248 is the specification family, /1 is the slash sheet (Class 1, 75 hardness fluorocarbon) and -214 is the AS568 size: 0.984 in inside diameter, 0.139 in cross-section. DoD cancelled the /1 sheet in 2008 and pointed future purchases to SAE AS3209 (boss sizes to AS3208); SAE later issued AS83248/1 (2014), an O-ring molded from AMS7276 material, which DoD adopted on 2025-11-03. The compound is AMS7276 either way, and the part is quoted against the number the print names. Read the family, then the slash sheet, then the dash. The M83248 family page walks through both classes.
How do I cross-reference a Parker 2-214 O-ring to a mil-spec part number?
The 2-214 is a size, not a material: Parker's dash numbers correspond with AS568, so 2-214 is the AS568-214 size. The mil-spec designator depends on the compound the print calls for, for example MS28775-214 for the petroleum hydraulic nitrile, M83248/1-214 for the 75 hardness fluorocarbon, or M25988/1-214 for the Class 1 Grade 70 fluorosilicone. Send us the Parker compound number printed beside the size and we cross-reference it to the document.
What is the AS568 equivalent of MS28775-214?
The -214 dash is already an AS568 dash: MS28775-214 is the AS568-214 size, 0.984 in inside diameter by 0.139 in cross-section, in the nitrile compound that MIL-PRF-25732 calls for. AS568 fixes the dimensions and MIL-PRF-25732 fixes the material. The SAE successor to the MS drawing is SAE-AS28775, whose title reads Packing, Preformed, MS28775 O-ring.
Which mil-spec O-rings have a QPL, and what does QPL-listed mean?
QPL-listed means a manufacturer's product has been tested and listed by the qualifying activity against the governing specification. On this page the government lists are QPL-25732 (MIL-PRF-25732, the MS28775 family) and QPL-25988 (MIL-DTL-25988, the M25988 family), both in DLA's Qualified Products Database. AMS7276 and AMS7259 carry SAE non-government QPLs. A distributor is never on a QPL; we supply parts made by the listed manufacturers and the listing shows on the certification.
Do I need a certificate of conformance with mil-spec O-rings?
You get one either way: a certificate of conformance ships with every order. It states that the part was supplied against the named document and carries the lot identification that ties it back to the manufacturer. Tell us on the request for quote what else the order needs, because those are the items a purchase order or a customer flow-down has to ask for: cure date, test reports or a first-article inspection report. We quote the certification with the part.
Is a cancelled MIL specification still a valid callout?
Yes. Cancellation is a standardization-office act and the part numbers stay on live drawings; buyers keep ordering MS28775 and M83248/1 by those numbers. The right answer is which document is current: the cancelled MIL document usually names its SAE successor in its own title, and the family pages here name it for you. Inactive for new design means the document is still maintained and still procurable but not for new designs; MIL-PRF-25732 and MIL-DTL-25988 are in that state; 25732 was revised in 2024 and 25988 carries a 2025 inactivation notice on its 2021 revision D.
Where can a small manufacturer buy mil-spec O-rings by part number with traceability?
From a distributor that quotes the designator as printed and supplies the part with the certification the document and your quality system need. Send us the callout, the quantity and the paperwork requirement; we quote the part in the compound the document calls for, made by the manufacturers listed for it where a qualified products list exists, with a certificate of conformance and lot traceability. Standard AS568 sizes cover every family on this page, and each dash has its own size page here.
Related guides
Sources
DLA ASSIST-QuickSearch document details (quicksearch.dla.mil), statuses, titles and supersession read 2026-09-24 and 2026-09-25; the NAS1611, NAS1612 and NAS1613 adoption records, the SAE-AS9385 withdrawal notice and the MS29512, MS9385 and MS9386 drawings read 2026-09-27; the MIL-R-83248/1A cancellation notice (Notice 5, 2008), read 2026-09-29; the inactive-for-new-design notices for MIL-P-25732C (Notices 1 and 2, 1989 and 2003, read 2026-09-25) and MIL-DTL-25988D (Notice 1, 2025, read 2026-09-28); the SAE-AMS-R-25988 withdrawal of adoption notice (2018), read 2026-09-28; SAE Mobilus public standard pages (saemobilus.sae.org), revision letters and dates read 2026-09-24 and 2026-09-25, and the current-revision records read 2026-09-27, whose AMS3304J, AMS7267H and AMS7276J titles give the hardness classes in the index; AIA standards store records for NAS1611, NAS1612 and NAS1613, and AIA's Purchase Standards page and its QPL answer, read 2026-09-27; DLA Qualified Products Database (qpldocs.dla.mil) for the QPL model; the DLA ASSIST QPL-25732 record (read 2026-09-25) for the 25732 list's existence; Parker O-Ring Handbook ORD 5700 (2021), Tables 8-3 and 8-4, for compound pairings and the dash correspondence; Section 4.5 for the boss series; Freudenberg Sealing Technologies aerospace part and material cross-reference brochure (2024), for the designation pattern, the standard-versus-boss dash split and the NAS -A suffix usage only; Parker O-Ring Handbook ORD 5700, 2021 printing, section IX, AS568 size tables, pages 9-2 to 9-11, read 2026-09-27. Statuses appear only where a publisher's own page was read; for any other document, ask with the quote. Facts are stated in our own words and our own arrangement; no standard's text or table and no manufacturer's cross-reference table is reproduced.
Parker is a trademark of Parker Hannifin Corporation. No affiliation or endorsement is implied.
Setting Conquest Seal up as a supplier?
Send the callout as the print reads it
Designator, slash sheet, dash, quantity and the certification the order needs. A Conquest representative replies with the part quoted against the document. Quotes answered within one business day. A person answers (714) 632-9830, Pacific business hours.
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