Invincible Marine BR59518 KeelRoller 10-Inchx5/8-Inch Blk Rubber Made using the highest quality components Performance and quality tested The most trusted name in marine accessories and equipment Allows your boat to roll smoothly on the trailer and spin freely to reduce drag while launching your boat Unaffected by oil, gas or salt Made of black rubber and 10-Inches by 5/8-inches in size Comes with a 1-year warranty