T51 89mm Flat Face Standard Body Ballistic Button Bit for Rock Drilling The T51 89mm Flat Face Standard Body Ballistic Button Bit is a top hammer threaded rock drill bit engineered for demanding rock drilling operations. It features a T51 threaded connection, an 89mm drilling diameter, a flat face design, a standard body profile and ballistic tungsten carbide buttons. The ballistic button configuration delivers an effective balance between rock penetration rate and wear