Faithfull Dry Diamond Core Bits combine a professional quality 1/2in BSP threaded core with premium 8mm fluted turbo cut diamond segments. They are manufactured to offer exceptional wear and speed of cut. The V-groove segments assist in clearing debris when in use. Ideal for use in plumbing, electrical and general building installations to cut clean holes in brick and concrete blocks. Suitable for rotary use ONLY Must not be used on percussion/hammer mode. For use with a power drill of 850 watts upward, equipped with a safety clutch and a variable speed function Do not use Diamond Cores larger than & Oslash78mm with SDS Plus drills as this may result in damage to the power tool or SDS adaptor. Diamond Cores give the best results when used with a purpose-built core drilling machine.