The thrust washer vibrates as the boat speeds up in choppy water. It is a must to choose the correct propeller hardware; if not, propeller shaft failures can occur. Forward Thrust Washer 990579 is a propeller thrust washer. It stops the boat propeller from sliding forward on the propeller shaft. The thrust washers withstand the axial force of great use for propeller shafts in boats as they allow the rotating propeller axial thrust as it moves forward and backward. Key Features: Michigan Wheels Forward Propeller Thrust Washer, 990579 It fits with Honda BF 35, BF 45 (1991-1994), BF 40, BF50/50A (1995 and Newer), and BF 60 (2010 and Newer) Compatible with Honda 35-60 HP outboard motors Suitable for Michigan Match and Original Equipment Manufacturer propellers not using the replaceable hub kits Product Specifications: Brand: Michigan Wheel SKU: 990579 UPC: 014984024921 Weight: 1.00 LBS Type: Propeller Thrust Washer Unit Of Measure: EA Condition: New Manufacturer Part Number: 990579 Replaces Product: 14984024921, 90506-ZV5-000