This reducer is made of raw steel and allows you to reduce the diameter of your bearing from 30 to 25 mm.
The central part that fits into the bearing measures 15 mm in height, and the shouldered part on top measures 3 mm in thickness.
The outer diameter of the piece is 40 mm. This piece is made with a precision of one hundredth of a millimeter, which prevents the ball bearing from getting stuck during rotation. Once installed on your wheel on each side, the wheel will therefore be 6 mm wider, which needs to be taken into account.