T51 102mm Flat Face Standard Body Ballistic Button Bit for Rock Drilling The T51 102mm Flat Face Standard Body Ballistic Button Bit is a threaded top hammer rock drill bit designed for demanding rock drilling applications. It features a T51 threaded connection, a 102mm drilling diameter, flat face design, standard body and ballistic tungsten carbide buttons. The 102mm diameter corresponds to approximately 4 inches and is a commonly available T51 drill bit size, widely offered