Hard anodized 31 tooth 7075 alum idler gear for the PRO2 SC10, RB10, SR10, B5, DR10, DB10 and similar platform Associated cars. This is much stronger than the stock plastic idler gear but not indestructible so it is important to use black or white grease on the gears and reapply frequently to prolong its life along with proper slipper adjustments.