These are the optional Factory Team Version 2 Slipper Hubs. Fits Associated B4.1FT, SC10FT, T4.1FT, B44.1FT and SC104x4, also fits B4, T4, SC10 and B44 with the #7486 (ASCC7486) V2 Slipper Spring and Washer Aluminum construction Vented for lighter weight and heat dissipation Two slipper hubs Installation on slipper clutch assembly Outer Diameter: 31mm (1.22") jxs 09/12/11 ir/jxs &