This Ski-doo TRA Spring Cover replaces your worn out spring cover bushing including a whole new cover on most Ski-doo 2008-2015 800 R's. The bolt hole tower casting's are 15mm tall on this spring cover so if yours measures the same this is the correct replacement. This bushing can be checked easily with your primary spring removed and the spring cover bolted back down. Any play in the moveable sheave can easily be felt and both the spring cover and moveable sheave bushing should be replaced. Moveable sheave bushings are available in our TRA rebuild kit.