Roller bit core barrel is used in very strong rock formations (compressive strength > 100 MPa). It uses welded roller bits for cutting the annular groove with a width of 220 or 320mm. The core barrel is extracted from the bore after coring a length of about 1m. 

200 kelly box made of heat-treated cast steel with two locking pins. Wear strips or Tungstuds wear protection on the barrel body. Fitted with brand new welded roller bits. Bottom ring in Hardox HB 500.