Ox Tools Superior Superfast Helix Dry Diamond Core Drill Bit Sizes 22mm to 200mm. Extremely durable dry diamond core drill bit made to drill into almost any material you might find on a construction site with no extra lubrication/liquid. Suitable for use with bricks, masonry, concrete blocks, general building materials, lightly reinforced limestone aggregate concrete and most natural stone. All the options refer to the size of the diameter. All the bits have a 1/2 BSP (F) back end apart from the 22mm (Hex) and 28mm (Hex) which have Hex back ends. The 22mm, 22mm (Hex), 28mm & 28mm (Hex) bits are 300mm in length and the rest of the bits are 150mm in length. All of the bits are compatible with most drills but extra accessories may be required for some bits/drills.