uxcell 20 Pcs White Plastic 0.5" Diameter Machanical Model Belt Pulley Product Name : Belt Pulley;Material : Plastic Color : White;Size : 13 x 4mm/ 0.5" x 0.16" (D*T) Fit Belt Width : 1.4mm/ 0.055" Weight : 10g Package : 20 x Belt Pulley