1/2in Shank.

By changing the bearing the size of the rebate can be altered.
Supplied with 4 bearings.
Use of :
19 mm Bearing gives rebate of 7.9 mm.
16 mm Bearing gives rebate of 9.5 mm.
12.7 mm Bearing gives rebate of 11.1 mm.
9.5 mm Bearing gives rebate of 12.7 mm

D = 35 mm
C = 12.7 mm