This variable pitch hole saw kit is manufactured from heavy-duty steel with 8% cobalt for extra strength and performance. Suitable for cutting holes in steel, brass, bronze, cast iron, aluminium, wood and plastics. Maximum cutting depth 38mm. Hole saw sizes 20, 22, 29, 35, 38, 44, 51, 57, 64mm (diameter). Kit includes 14-30mm and 32-152mm hex. arbors and 4mm hex. key. Supplied inside a blow moulded plastic storage case. 8% cobalt for extra strength and performance Variable pitch teeth 38mm cutting depth Sizes 20, 22, 29, 35, 38, 44, 51, 57, 64mm (diameter) Includes 14-30mm and 32-152mm hex. arbors and 4mm hex. key Supplied inside a sturdy plastic storage case Cutting depth: 38mm Pitch: 4.5-5tpi