T38 Thread 64mm Diameter Retrac Skirt Threaded Button Bit Rock Drill Bit For Abrasive Rock Drilling This top-hammer rock drill bit delivers stable drilling performance in abrasive rock conditions, prioritizing long service life, straight hole alignment, and reliable penetration. As a core offering from our Henglong threaded bit lineup, it covers a wide diameter range from 28 mm up to 152 mm, with custom carbide grades built for heavy rock work. Specifications Thread T38