MALCO MAL-HSK - HVAC Starter Kit (16-Piece)Product Overview The Malco HSK is a Bi Metal Hole In One kit that provides you with a hole saw selection, pilot drills, arbor extension and driver. The kit comes complete in a durable polyproylene case. Includes 4 HSB drills, HSX extension arbor shank Stubby driver One each of the following hole saw sizes: 2 1 2" (63. 5mm) 2 1 4" (57. 2mm) 2" (50. 8mm) 1 3 4" (44. 5mm) 1 1 2" (38. 1mm) 1 3 8" (34. 9mm) 1 1 8" (28. 6mm) 7 8" (22. 2mm) 3 4"