NEW G-Force Carbon Drive Belts are proving to be a great replacement for Ski-doo 377,391,383,288, 513, 571 drivebelts and fit all applications of Ski-doo Rev, XP, XS, XM sleds. This belt is slightly shorter and slightly wider than the Ski-doo 391. The length is listed at 43-7/8". It is showing better top speed and good wear characteristics with the carbon cord design. Users have reported no changing rpm issues with this belt as is common with other belts.