25 (optional 50, 75, 100, Bulk) Mercury Racing Quicksilver Marine Mariner Mercruiser Thick Flat Case Hardened Beveled Stainless Steel Speciality WASHERS .875 x 0.435 x x 0.100 This washer is found on many lower units, gearcases, sterndrives, IO (Inboard / Outboard) drives, gimbal housing and mid-section assemblies with 7/16" studs that require the right sized washer to fit the marine engine assemble correctly. These are also used in other marine and non-marine industrial applications including military, aerospace, and agricultural. Matching part numbers are 12-35935,12-25410, 35935, 8M0204655,12-8M0204655
Note: Case hardening is a heat treatment process that hardens the surface of a metal part while keeping the inside of the part relatively soft. The process involves adding a thin layer of carbon or nitrogen-enriched surface to the parts. The harder alloy on the outer surface is called the case, while the inner structure is called the core. Case hardening is ideal for objects that need to have a hard exterior to deal with everyday wear and tear, while also retaining their flexibility.