S2M aluminum synchronous belt pulley can transmit power of motor to synchronous belt to drive the mechanism, mainly used in small precise mechanical transmission like 3D printers. Specification: Model: S2M-20 Teeth Pitch : 2mm Bore Diameter : 5mm Bore Outside Diameter : 16mm Fit Belt Width : 6~8mm Overall Size : 16 x 16mm (D*H) Material : Aluminum Alloy; Color : Silver Tone Package Content : 1 x Timing Pulley Weight: 9g