Complete 11 piece holesaw kit: eight carbon steel hole saws from 19mm to 64mm plus an HSS pilot drill bit and arbor, so one compact set covers downlights, pipework, cable runs and door hardware without buying separate hole cutters. Eight sizes stamped on the blades: 19mm (3/4 inch), 22mm, 28mm, 32mm, 38mm, 44mm, 51mm and 64mm (2.5 inch), matching common UK downlight, waste pipe and grommet diameters, so you can pick the right cutter at a glance and cut accurately first time. Built for boards rather than steel: the carbon steel teeth cut clean, splinter free holes in softwood, hardwood, plywood, MDF, plasterboard, drywall and plastic sheet, and will take thin aluminium. Structural steel needs a bi-metal blade instead. Fits any drill in seconds: mount the blade on the arbor, tighten the nut with a spanner rather than by hand, then load the shank into a corded or cordless chuck. Finger tight is the usual reason a blade works loose part way through a cut. Let the drill do the cutting: run at a moderate speed, ease off the pressure and back out to clear the dust and the plug. Pushing hard is what blunts a carbon steel tooth. Treated properly the set covers a full house of spotlights and cable runs.