Wheel Master alloy, sealed bearing wheelchair hubs Wheel Building Specs: Hub width: 64.5mm Flange to inset bearing: 10.5mm Flange diameter: 54mm Bearing size: 28.6mm OD , 12.7mm (1/2`) ID Whl Chr 36H 1/2` (12mm) Aly Blk 45.5 45.5UPC/EAN/GTIN: 072774360758