C-type Boring head with 20 mm Boring Tool 

Graduation 1 Div. = .01 mm

Boring Hole 20 mm

Offset - 25mm

Boring Capacity - 20 mm to 200 mm

Back Thread - 1.5" x 18 TPI

Can be used with different Shanks R8,MT2,MT3,ISO30,ISO40,BT40,BT50,ETC.

You can use indexable boring bar with 20 mm shank to start minimum diameter of boring.  Length of the boring should be LD3 if boring bar is 20 mm depth of boring should limit to 60 mm in order to escape chattering.