8 mm to 1/2 in. Hex Shaft AdapterThis adapter converts an 8 mm keyed shaft to 1 2 in. hex. Description Specifications Documentation The keyway is 2 mm wide. This allows you to adapt the output of a motor or gearbox like the CIM Motor (am 0255) to any of our hubs or wheels with a 1 2 in. hex bore. You'll need a 2 mm machine key (am 1121) to complete the assembly and transmit torque from the motor. Bore: 8 mm [0. 31 in.] Round Keyway Width: 2 mm Length: 0. 5 in., 1 in. Material: Steel