Expert quality for use with most variable speed rotary or stationary pillar drills sturdy construction with transparent cowl to retain flying debris whilst drilling especially useful when drilling ceilings etc supplied with pilot drill and hexagon key for easy radius adjustment cuts plywood plasterboard acrylic sheet up to 23mm depth 45mm if drilled from both sides aluminium brass and sheet metal up to 1mm depth maximum speed for cutting holes up to 115mm diameter is 900rpm up to 163mm 500rpm