11pcs Diamond Core Drill Bits Set. This Heavy Duty Diamond core set is the ideal tool for making holes in concret, refractory marble, granite etc. Designed for wet or dry coring, with top quality finishing that provides a long life and high efficiency with this core drill. Comes in durable reinforced box. 5 core drills (38, 52, 65, 117, 127mm). Includes Hex and SDS plus arbours. 1/2 inch BSP 25mm solid extension. 13mm A Taper Drill. Guide rod and Drift key. Angled slots extend through back end to expel dust Unique’Helix’ barrel design draws dust down the barrel Working deep 150mm.