Specifications:
Model: 0.5 Modulus
Teeth: 8T 9T 10T 11T 12T 13T 14T 16T 18T 20T
Bore: 1.95mm

Size:
0.5Mod 20T, Inner diameter: 1.95mm; Tooth length: 5mm; Round diameter: 11mm
0.5Mod 18T, Inner Diameter: 1.95mm; Tooth Length: 4.5mm; Round Diameter: 10mm
0.5Mod 16T, Inner diameter: 1.95mm; Tooth length: 5mm; Round diameter: 9mm
0.5Mod 14T, Inner Diameter: 1.95mm; Tooth Length: 5mm; Round Diameter: 8mm
0.5Mod 13T, Inner Diameter: 1.95mm; Tooth Length: 5mm; Round Diameter: 7.5mm
0.5Mod 12T, Inner diameter: 1.95mm; Tooth length: 5mm; Round diameter: 7mm
0.5Mod 11T, Inner Diameter: 1.95mm; Tooth Length: 5mm; Round Diameter: 6.5mm
0.5Mod 10T, Inner diameter: 1.95mm; Tooth length: 5mm; Round diameter: 6mm
0.5Mod 9T, Inner Diameter: 1.95mm; Tooth Length: 5mm; Round Diameter: 5.5mm
0.5Mod 8T, Inner Diameter: 1.95mm; Tooth Length: 5mm; Round Diameter: 5mm 

Packing quantity: 10/20/50/100/200/500pcs

You can choose the value you want from the drop-down box above.