Size-----Totally 10pcs/set: diameter 5/5/6/6/6/6/8/8/10/12mm; total length 90mm; cutter head length 9/11/14/17/20mm; working length 54mm; quick change hex shank; handle diameter 6.35mm Application-----Dry drilling materials (softer materials) are wood, plastic (PVC pipe), foam tiles, antique tiles, glazed tiles, red bricks, cement, concrete (need to avoid reinforcing steel), etc; need to add water or coolant drilling materials (harder materials) are glass tiles, porcelain tiles, ceramics, marble, glass, etc Slant Head Eccentric Design-----Ensures precise positioning, fast and efficient drilling, reduced wear and tear, and longer service life. Spiral grooves in the head for easy chip removal. It can be used for drilling on the one hand and assisting other drills for accurate drilling and positioning on the other hand High Quality Material-Tungsten Carbide-----The tip of the drill is welded with high-grade industrial-grade tungsten carbide, which has good abrasion resistance and can easily penetrate various materials. The drill body is made of selected high-strength steel matrix, which can effectively assist drilling and has a long service life Recommended Machine-----Corded Drill, Cordless Drill, Benchtop Drill. Use electric hand drill: Recommended speed not less than 2000RPM; Faster the RPM, longer the drill bit's working life. When use Angle Grinder, please install angle grinder drill chuck