Ox Tools Premium Dry Diamond Core Drill Brick Vent Flue 22mm to 182mm. Universal dry diamond core drill in all popular plumbers sizes. 1/2 BSP female thread takes Spectrum dry core accessories. Slotted barrel provides efficient dust clearance and ease of removing drilled core. Sizes Available – 22mm, 28mm, 32mm, 38mm, 48mm, 52mm, 65mm, 78mm, 91mm, 102mm, 107mm, 117mm, 127mm, 142mm, 152mm, 162mm, 172mm and 182mm. For brick and blockwork. Applications include: Medium and soft bricks, concrete blocks (lightweight and dense), abrasive concrete products. Occasional use in harder materials e. Semi engineering bricks and clay products.