Halo Mxr-Fw Freewheel Rear Hub, (3/8 inch) 36H Red - HUHABT6R All feature a forged/CNC 6061-T6 aluminum shells with sealed cartridge bearings MXF front has a 15mm hollow alloy axle with 3/8" bolts MXF front has a 15mm hollow alloy axle with 3/8" bolts MXRC SupaDrive-Cassette rear uses 120-point triple wedge pawl system with a bushed singlespeed casse MXR-FW Freewheel rear accepts 1.37"x24t threaded freewheels (15mm hollow alloy axle with 3/8" bolts