20 Shape: S3 Reference circle diameter (mm): φ10 Tooth width (mm): 4 Module: 0.5 Hole diameter A (mm): φ3 Tooth tip circle diameter: 11 Total length (mm): 8 Hole diameter A' (mm): φ3.1 Boss diameter (mm): 11.4 Tooth tip circle diameter (mm): φ11 Boss length (mm): 4