C-type Boring head with 25 mm Boring Tool 

Graduation 1 Div. = .01 mm

Boring Hole 25 mm

Offset - 40mm

Boring Capacity - 25 mm to 250 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 25 mm shank to start minimum diameter of boring.  Length of the boring should be LD3 if boring bar is 25 mm depth of boring should limit to 75 mm in order to escape chattering.