Hougen RotaCut's are far superior to twist drills and hole saws. They cut 3x faster and last 10x longer; plus there's no comparison in quality. Use with hand held drills with a 3/8 or 1/2" chuck for holes in sheet metal; plate materials; and plastics up to 1/4" thick. Ideal for: Electrical; Piping; Conduit Work; Sheetmetal Fabrication; Spotweld Removal; Maintenance Installations; HVAC; PHCC; Automotive Aftermarket and many others... Includes: 11088 Arbor Assembly; Center Punch; extra Pilot; Cutter sizes (6; 7; 8; 8.5; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; & 20mm) and case." Hougen 11,000 RotaCut Metric Master Cutter Set 11086