Mil-spec O-ring family, fluorosilicone, four slash sheets
M25988 O-rings: fluorosilicone 60, 70, 75 and 80 to MIL-DTL-25988
M25988/X-XXX is a fluorosilicone (FVMQ) O-ring for oil and fuel service under MIL-DTL-25988, the same document as MIL-R-25988. The slash sheet sets the class and grade: /1 is Class 1 Grade 70, /2 is Class 3, /3 is Grade 60 and /4 is Class 1 Grade 80. The base document is inactive for new design, the four slash sheets are Active, and a government qualified products list, QPL-25988, exists.
- Polymer
- Fluorosilicone (FVMQ)oil and fuel resistant
- Durometer
- 70, 75, 60, 80/1, /2, /3, /4
- Documents
- MIL-DTL-25988/1 to /4Active, 2026-04-21
- QPL
- Yes, QPL-25988government, DLA QPD
Specification: documents, status, material
| Item | Value | Source |
|---|---|---|
| Base document | MIL-DTL-25988 (= MIL-R-25988), fluorosilicone, oil and fuel resistant, sheets, strips, molded parts and extruded shapes: Inactive for new design, revision D Notice 1, 2025-06-11; the record carries a Qualification link | DLA ASSIST ident 18213, read 2026-09-13 |
| Slash sheet /1 | MIL-DTL-25988/1, O-rings, Class 1, Grade 70: Active, revision B Notice 1 (validation), 2026-04-21 | DLA ASSIST ident 18214, read 2026-09-13 |
| Slash sheet /2 | MIL-DTL-25988/2, O-rings, Class 3: Active, revision A Notice 1 (validation), 2026-04-21 | DLA ASSIST ident 18215, read 2026-09-13 |
| Slash sheet /3 | MIL-DTL-25988/3, O-rings, Grade 60: Active, revision A Notice 1 (validation), 2026-04-21 | DLA ASSIST ident 18216, read 2026-09-13 |
| Slash sheet /4 | MIL-DTL-25988/4, O-rings, Class 1, Grade 80: Active, revision A Notice 1 (validation), 2026-04-21 | DLA ASSIST ident 18217, read 2026-09-13 |
| SAE parallel | SAE-AMS-R-25988: Revised, current AMSR25988B, 2023-06-27; DoD withdrew its adoption effective 2018-01-02 while SAE kept revising (withdrawal of adoption is not cancellation) | SAE Mobilus; DLA ASSIST notice |
| Related SAE material | SAE-AMS3325, fluorosilicone 55 to 65: current AMS3325H, 2024-09-11; the legacy cross-reference for the /3 grade | SAE Mobilus, read 2026-09-06 |
| Base polymer | Fluorosilicone (FVMQ) | document titles |
| Durometer | /1 = 70 and /4 = 80 (Grade in the titles); /3 = Grade 60 (title); /2 = Class 3, supplied at 75 by manufacturers (the title prints no grade) | DLA ASSIST titles; Parker® ORD 5700 (2021) |
| Boss variant | None on record | DLA ASSIST and SAE Mobilus, read 2026-09-06 |
| QPL | Yes, government: QPL-25988 in DLA's Qualified Products Database; ask with the quote for the current list | DLA ASSIST, read 2026-09-13 |
| Service | Oil and fuel resistant (the document title) | document title |
| Compounds manufacturers pair with this document | Parker ORD 5700 (2021) Table 8-3 pairs LM159-70 with Grade 70 (/1), L1077-75 with Class 3 Grade 75 (/2), LM158-60 with Grade 60 (/3) and LM160-80 with Grade 80 (/4); Table 8-4 lists the same four against AMS-R-25988 and LM158-60 against AMS3325 | Parker ORD 5700 (2021) |
Status strings are quoted as DLA ASSIST and SAE Mobilus print them (Canceled is ASSIST's spelling; Inactive means inactive for new design; Withdrawn is SAE's word). Conquest Seal is a distributor and is not itself listed on any qualified products list.
Designator to AS568 size
M25988/1-XXX, /2-XXX, /3-XXX and /4-XXX are the AS568-XXX size, per the manufacturers' cross-references; the slash sheet changes class and grade, never the size. No boss variant is on record.
| M25988/1 | M25988/2 | M25988/3 | M25988/4 | AS568 dash | ID in | W in | ID mm | W mm |
|---|---|---|---|---|---|---|---|---|
| M25988/1-006 | M25988/2-006 | M25988/3-006 | M25988/4-006 | AS568-006 | 0.114 | 0.070 | 2.90 | 1.78 |
| M25988/1-010 | M25988/2-010 | M25988/3-010 | M25988/4-010 | AS568-010 | 0.239 | 0.070 | 6.07 | 1.78 |
| M25988/1-012 | M25988/2-012 | M25988/3-012 | M25988/4-012 | AS568-012 | 0.364 | 0.070 | 9.25 | 1.78 |
| M25988/1-112 | M25988/2-112 | M25988/3-112 | M25988/4-112 | AS568-112 | 0.487 | 0.103 | 12.37 | 2.62 |
| M25988/1-114 | M25988/2-114 | M25988/3-114 | M25988/4-114 | AS568-114 | 0.612 | 0.103 | 15.54 | 2.62 |
| M25988/1-116 | M25988/2-116 | M25988/3-116 | M25988/4-116 | AS568-116 | 0.737 | 0.103 | 18.72 | 2.62 |
| M25988/1-210 | M25988/2-210 | M25988/3-210 | M25988/4-210 | AS568-210 | 0.734 | 0.139 | 18.64 | 3.53 |
| M25988/1-214 | M25988/2-214 | M25988/3-214 | M25988/4-214 | AS568-214 | 0.984 | 0.139 | 24.99 | 3.53 |
| M25988/1-222 | M25988/2-222 | M25988/3-222 | M25988/4-222 | AS568-222 | 1.484 | 0.139 | 37.69 | 3.53 |
| M25988/1-325 | M25988/2-325 | M25988/3-325 | M25988/4-325 | AS568-325 | 1.475 | 0.210 | 37.47 | 5.33 |
Millimeter values are converted from the inch table. The dash is a size lookup and never a material; the same dash on another family on the mil-spec hub is the same size in a different document. Full chart: AS568 size chart.
Where the documents stand
MIL-R-25988 became MIL-DTL-25988 by prefix change; it is one government record for fluorosilicone sheets, strips, molded parts and extruded shapes, and the four slash sheets are its O-ring sheets. DLA ASSIST lists the base document inactive for new design at revision D Notice 1 of 2025-06-11, while each slash sheet carries a validation notice dated 2026-04-21 and reads Active, with the /4 sheet's next review set for 2031. SAE's parallel AMS-R-25988 had its DoD adoption withdrawn on 2018-01-02, and SAE then issued revision B in 2023; the document is alive, only the adoption ended.
So the M25988 callouts are current on both sides: government slash sheets that are Active and carry QPL-25988, and an SAE material document at revision B. There is no supersession to a different number. Quote the slash sheet the print names.
The base polymer
The polymer behind this family is fluorosilicone (FVMQ). The Parker O-Ring Handbook ORD 5700 family range on file for Fluorosilicone (FVMQ) is -73 C to 177 C; that is the polymer family's range, not this document's requirement, and the compound sheet for the qualified grade governs. Parker notes that specification temperature limits do not necessarily represent operating temperature limits.
Material page: Fluorosilicone (FVMQ) O-rings. Temperature ranges by family: O-ring temperature ranges.
How we quote this family
Send the designator as printed with its slash sheet, for example M25988/1-XXX, with the dash, the quantity and the certification the order needs. We quote it supplied against MIL-DTL-25988 and the named slash sheet (or AMS-R-25988 where the print calls the SAE document), in the fluorosilicone class and grade the sheet calls for, made by QPL-listed manufacturers, with a certificate of conformance and lot traceability. If the print gives a class and grade instead of a slash sheet, we map it: Class 1 Grade 70 is /1, Class 3 is /2, Grade 60 is /3, Class 1 Grade 80 is /4.
Related pages
Other families: MS28775, M83461/1, M83248/1 and M83248/2, M83485/1, MS29513 and MS29512, NAS1611 and NAS1612, AS3582, AS9386 and AS9385, AS3209 and AS3208.
Frequently asked
What is an M25988/1 O-ring made of?
Fluorosilicone (FVMQ), Class 1 Grade 70, under MIL-DTL-25988/1, an oil and fuel resistant document. The slash sheet is Active with a validation notice of 2026-04-21, and the base document carries QPL-25988. Parker ORD 5700 (2021) pairs LM159-70 with the Grade 70 line.
What is the difference between M25988/1, M25988/3 and M25988/4?
Grade, which is hardness: /1 is Class 1 Grade 70, /3 is Grade 60 and /4 is Class 1 Grade 80, as the DLA ASSIST titles print them; /2 is Class 3, which manufacturers supply at 75. All four are the same fluorosilicone polymer in the same AS568 sizes. Parker ORD 5700 (2021) pairs LM158-60, LM159-70, L1077-75 and LM160-80 with the four sheets.
When should I use a fluorosilicone O-ring instead of fluorocarbon?
When the print or the system specification calls for it; the document decides. As polymers, fluorosilicone keeps the flexibility of a silicone at low temperature while adding fuel and oil resistance, and fluorocarbon covers a wider chemical range at high temperature. The Parker ORD 5700 family ranges on the material pages show where each polymer sits. The choice belongs to your print or your system specification; send the callout it names and we quote that part.
Is MIL-DTL-25988 still active?
The base document is inactive for new design at revision D (inactivation notice 2025-06-11), which means maintained and procurable but not for new designs. The four O-ring slash sheets /1 to /4 are Active, each with a validation notice dated 2026-04-21. SAE's parallel AMS-R-25988 is current at revision B of 2023. The callouts stay valid.
Does M25988 have a QPL?
Yes, a government one: QPL-25988 in DLA's Qualified Products Database, and the DLA ASSIST record for MIL-DTL-25988 carries a Qualification link. We supply parts made by the listed manufacturers and the listing appears on the certification. The DLA database is searched by governing specification.
Related guides
Sources
DLA ASSIST document details, idents 18213 (MIL-DTL-25988), 18214, 18215, 18216, 18217 (slash sheets /1 to /4), read 2026-09-13; SAE Mobilus: AMSR25988B (2023-06-27), AMS3325H (2024-09-11), read 2026-09-06; Parker O-Ring Handbook ORD 5700 (2021), Tables 8-3 and 8-4, for the compound pairings; AS568 dimensions from this site's size chart. 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. Compound pairings are the named manufacturer's published statements, not qualified products list entries.
Parker is a trademark of Parker Hannifin Corporation. No affiliation or endorsement is implied.
Need M25988/1, /2, /3 and /4 with certification?
Send the designator as the print reads it, the dash, the quantity and the paperwork the order needs. A Conquest representative replies with the part quoted against the document.
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