Our SeaSense Black Rubber 10-Inch Keel Roller allows your boat to roll smoothly on the trailer. Roller spins freely, to reduce drag while launching your boat. Features a 5/8" shaft size with durable black rubber construction. This keel roller is designed to easily handle marine conditions, and the tough rubber construction stands up to oil, gas and salt. Dimensions 5/8" x 3-1/2" x 9-1/2".