... face design and button insert types.Thread button bitsDescription:suitable for powerful percussive drills and top hammers with high speed ... special heat treatment ,especially, tungsten carbide of tapered button bits are from Boart long year, widely applied ... quarry and Norway, Finland quarry.Tapered button drill bit specifications : Type: button bitsSize: 19mm,22mm,25mmDiameter: 30-42mm.Taper degree: ...