Part Number
O-Ring · Military specification (M-prefix) · NSN 5331-01-033-5799
| Part number | M25988/1-166 |
|---|---|
| Specification family | Military specification (M-prefix) |
| Item name | O-Ring |
| Alternate references | MIL-DTL-25988/1; MIL-R-25988/1 |
| Unit of issue | EA |
| Cross-referenced NSN | 5331-01-033-5799 |
| Federal Supply Class (FSC) | 5331 — O-Rings |
| Unit price (USD) | $26.28 |
| Country of origin | Türkiye (Turkey) |
| Lead time | Within 90 days of order |
| Minimum order | May apply — confirm on quote |
| Documentation | Source documentation provided on all orders |
Characteristics decoded from the federal cataloging record for this o-ring. Confirm controlling dimensions against your drawing or standard sheet before ordering.
| Cross-Sectional Height | 0.100 Inches Minimum And 0.106 Inches Maximum |
|---|---|
| Hardness Rating | 70.0 Shore Durometer A Nominal |
| Material | Rubber Fluorosilicone Class Fq |
| Outside Diameter | 6.943 Inches Nominal |
Precision elastomeric sealing rings of circular cross-section used for static and dynamic sealing in grooves and glands.
Reading the part number. M25988/1-166 is a military-specification slash-sheet number: it points to slash sheet 1 of MIL spec 25988, and the remaining characters (166) encode the size, material, and finish options that sheet defines. Ordering by this number pins down the exact variant of the o-ring.
Price in context. Across the 692 items we currently stock in FSC 5331 (O-Rings), published unit prices run from $0.14 to $3,504.60. At $26.28, this item sits well above the class median of $5.25 — typical of assemblies and higher-value line items in this class.
Who orders M25988/1-166. Aircraft owners and MRO shops replacing standard hardware, machine shops and OEMs filling a bill of materials, and government contractors sourcing against NSN 5331-01-033-5799. You can order by part number or by stock number — it is the same item, the same published price, and the same quote form.
Applicable standards. AS568 dash sizes, MIL-P-5510 / SAE AS5857; nitrile, fluorocarbon (Viton), EPDM, and silicone compounds.
Need this part modified, or a similar part made to your print? See our U.S.-based CNC machining services and aerospace machining capability.
Country of origin: Türkiye (Turkey) — a DFARS qualifying country. Türkiye is a NATO ally with a reciprocal defense procurement agreement with the U.S. Department of Defense, making it a qualifying country under DFARS 225.003. On DoD and DLA solicitations, qualifying-country end products are evaluated without Buy American price penalties — they compete on par with domestic product — and DoD trade-agreements clauses (DFARS 252.225-7021) expressly accept qualifying-country end products.
Dollar thresholds. The Trade Agreements Act only applies to supply contracts at or above $174,000 (the WTO GPA threshold effective March 2026); below that — where the vast majority of hardware buys fall — the TAA does not apply at all. The main exclusion is civilian-agency solicitations at or above that threshold that restrict award to TAA designated-country products (Türkiye is not TAA-designated). Buyers are responsible for confirming the origin requirements of their specific solicitation.
Full country-of-origin and source documentation is provided with every order. Fulfillment within 90 days of order. Minimum order may apply.
Items are supplied as stock mil-spec / commercial hardware with source documentation and country-of-origin paperwork on every order. Parts are not supplied with an FAA Form 8130-3 airworthiness tag unless expressly stated on the quote. Buyers installing hardware on certificated aircraft are responsible for acceptance under their own maintenance program, repair station procedures, or owner/operator authority.
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