MK Diamond MK-DRY premium core bits are specifically designed to tackle a variety of soft brick and concrete block drilling operations. These MK-DRY premium core bits feature laser-welded technology and inventive bar-slot cooling to promote efficiency, reliability and safety in core drilling. The MK-Dry premium core bits are 10" in length, come with standard 5/8"-11 threaded nuts and are easily attached to most hand-held drills.