BoxTurtle-HexDrive Hexagonal axles for the BoxTurtle respooler to prevent slipping Bill of materials num description 4 7mm hex shafts, such as , $7.49 for four 8 (optional) 7mm hex bearings, such as , $5.99 for two 8 M3 x 8mm socket head screws 8 M3 brass heat-set inserts