BDL's 11mm belt drives have been around for many years. Most belt drive enthusiasts still think that these are the best size and combination for all around riding and dependability. This drive adapts your stock clutch directly into our basket or you can choose to upgrade your clutch to BDL's Competitor Clutch #CC-100-S for 30% more clutch surface area than the stock clutch. Our 47-31TK-1 fits Knucklehead and Panhead kick start models 1936-1954.