... Known for their reliability and logerity. PRODRILL thread button bitsRope thread:R32, R33, R38, R35T thread: T38, T45, T51, ST58, T60 ... - manufactured with a middle stop to prevent walking along the thread. Include couplings sleeve (threaded R22, R25, R28, R32, ... heat treatment & stress relief process, especially premium carbide inserts supplied by Boart Longyear, which place our bits far ahead ...