Sierra 18-7921 Oil Filter Sierra replacement canister oil filter for Mercury Marine engines. Fits 135150175200 HP Verado In-line 4 cylinder OB. Anti-Drain-Back Valve Engineered with premium grade materials that will excel in the extreme marine environment Epoxy coated for corrosion resistance Heavy-wall steel canister for further corrosion protection High-efficiency filter media that meets or exceeds the OEs filtration Backed by Sierras industry leading warranty Thread Spec 24mm x 1.5 Interchang