Hope Pro 4 Front Disc Hub 110 x 15mm for Boost, 32h, Black Taller Flanges than the Pro 2 with no increase in weight for stiffer wheel builds Taller Flanges than the Pro 2 Additional end caps sold separately Equipped with stainless steel bearings Boost Hubs are only compatible with Boost 15mm Thru Axle x 110mm Forks