This RAM rubber ball base replaces one of your M8 bolts. All you have to do is screw the ball base onto your handlebar top clamp using one of the three bolt options (included) all of which have an M8 (1.25mm) thread pitch.
Includes: rubber mounting ball, three X 1.25mm thread pitch bolts (sizes M8 X 55mm, M8 X 60mm, M8 X 65mm – which are designed to replace your M8 X 30mm, M8 X 35mm or M8 X 40mm bolts respectively).
Ball size: 1” diameter (b-size)