THUNDER PRODUCTS SKI-DOO TRA Replacement primary rollers for worn stock rollers. These are high quality "made in USA" rollers available in stock diameter, 1mm oversize and 2mm oversize. Any wear or freeplay in your rollers drastically affect the performance of your clutches. We recommend these be checked each season and replaced as needed. These are the highest quality precision sized rollers sold as a set of 3 to do each TRA arm in your clutch.