Product Name: 4Kit Synchronous Wheel 20&30 Teeth 5mm Bore Aluminum Timing Pulley with 4PCS Length 200mm Width 6mm Belt Number of tooth: 20&30T Application:Widely used in milling machine, gear shaper, drilling machine, hobbing machine or other machinery transmission occasions Bore Diameter: 5mm/0.19inch Length of timing belt: 200mm/7.9inch Width of timing belt: 6mm/0.24inch Material: aluminum colour: silver Package Contents: 4 x 30 Teeth 5mm Bore Synchronous Wheel 4 x 20 Teeth 5mm Bore Synchronous Wheel 4 x Length 200mm Width 6mm Belt 8 x screws 2 x Hex Key Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.