... precision micro boring bar(micro boring head) 1.high precision, lots of types 2.the boring head with shank BNJ16 type micro boring bar(micro boring head) 1 ... .high precision, lots of types2.the boring head with shank3. ... as BHC3+BT40/50, BHC3 + NT30/40/50, BHC3 + MT2/3/4/5. BNJ16 type micro boring bar(micro boring head)