Box Components Hollow 20mm Front Race HubMarc Willers, Caroline Buchanan, Kurt Pickard, the Dutch National BMX team and many other of the worlds top elite and amateur racers have been winning on BOX strong 20 Millimeter Freewheel Hubs for more than two years, including a World Championship and three medals this year in New Zealand. Their more reliable and weigh less than many cassette hubs and, most importantly, have 20 millimeter axles. Box's race proven 20 mil axles help transmit more