Sierra 18-4233 Mercury Propeller Thrust WasherSierra high-quality engine parts are designed to meet OEM specifications. Fits Mercury 40-60 Standard Gearcase. Use with rubber props only; do not use with Flo-Torq reflex propellers.; For use with 3 blade stainless steel - Clever or Chopper II; Interchangeable with: Chrysler/Force/US Marine; 73345A1; GLM; 21290; Mercury Marine; 73345A1; 12-92647M; 73345;