Bosch HSM15PCE 15-piece Bi-metal Hole Saw Sheet Metal Set Set includes six hole saws meauring in inches: 7/8, 1-1/8, 1-3/8, 1-3/4, 2 and 2-1/2 Cobalt pilot bit is 3-3/8-inch Includes four adapters ranging from 1-1/4-inch to 6-inches Also includes two adapters measuring 9/16-inch and 1-3/16-inch Mandrel springs are 3/8-inch mandrel springs for hole saws from 1-3/4-to-6-inches Set Includes: (6) hole saws: 7/8-Inch, 1-1/8-Inch, 1-3/8-Inch, 1-3/4-Inch, 2-Inch, 2-1/2-Inch 3-3/8-Inch cobalt pilot bit (4) adapters 1-1/4-Inch 6-Inch (2)adapters 9/16-Inch, 1-3/16-Inch 3/8-Inch mandrel springs for hole saws from 1-3/4-to-6-Inch