R25 64mm Flat Face Button Bit for Rock Drilling The R25 64mm flat face dome button bit is a top hammer rock drilling tool designed for heavy-duty underground tunnelling, drifting and small-hole bench drilling in medium to extremely hard rock formations. Built with a flat face profile and a heavy-duty 12-button arrangement, this 64mm (2.5 inch) bit delivers high drilling stability, clean hole alignment and excellent wear resistance under high-impact percussion. Product