Shaft Usage: 8mm to 16mm / 0.31 to 0.63 inch Material: Aluminum alloy; Size: 40x32mm/ 1.57x1.26inch( L*D) Feature: Screw type (coiling clamping); Main Color: Silver tone Flexibility of coupling shaft removes stress between the motor and driving components. The shaft couplers are widely applied to small CNC machines encoding and 3D printers Z shaft coupling, simplifies the debugging difficulty.