Core barrels are used to cut an annular space in hard rock, boulders or concrete. In order to break the upcoming material with high tension, torque and feed force are concentrated on a relatively narrow ring. Depending on the strength of the rock and the drill diameter, the toothing of the core barrel can be adjusted: For concrete and rock with unconfined compressive strengths up to approx. 100 MPa, core barrel with welded-on carbide pins or studs are used. Alternatively, core barrel with round shank bits are suitable for this purpose. For drilling in compact rock with unconfined compressive strengths from 100 MPa to over 250 MPa, LEFFER core barrels with roller bits have proven to be the best choice.