Bass Pro Shops rollers are made of a durable molded polymer blend and are non-marring, so you can snug your boat down on the trailer. Unaffected by oil, gas or salt. UV protected. Per each. Available: Bow Roller - 4 L x 1/2 Shaft, Bow Roller - 3 L x 1/2 Shaft, Bow Stop - 3 L x 1/2 Shaft, Spool Roller - 5 L x 5/8 Shaft, Keel Roller - 12 L x 5/8 Shaft, Super Bow Roller - 3 L x 5/8 Shaft, Super Bow Roller - 4 L x 5/8 Shaft. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Rollers.