1/2" 3/4" Demi Bullnose 1-3/8" 2" diamond core drill bit stone concrete lapidary

(a) 1 Piece of B13 (13 mm / 1/2" Radius / Demi / Half Bullnose) Diamond Brazed. (b) 1 Piece of B20 (20mm / 3/4" Radius / Demi / Half Bullnose) Diamond Brazed. -with water feed hole, can be wet use.

eBay