Value Collection 21MP0126FA-3/16 Timing Belt Pulleys; Pulley Type: Hub & Flanges; Number of Teeth: 21; Outside Diameter (Decimal Inch): 0.5150; Material: Aluminum; Pitch Diameter: 0.535 in; 0.535 mm; Face Width: 0.26 in; 0.26 mm; Flange Diameter: 0.7