What is it for?
A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth, which mesh with another toothed part to transmit torque and speed.
 
Specs:
Material: Metal

A = 53 mm O.D.
B = 33 mm
C = 15 mm I.D.
D = 12.5 mm
E = 15 mm
F = M6 – 1.0
G = 5 mm Opening