Standard Pack = 1 piece(s). Featuring high-speed steel cutting edges, these Hole Saws have shock-resistant teeth that resist stripping. Made of M42 Cobalt bi-metal material, they also use a 4/6 positive-tooth configuration for fast, smooth cuts and less vibration. Other features include a 1 7/8" depth of cut and a 3/16"-thick heavy-duty backing plate that eliminates the need for a drive plate. Sold individually (boxed). Model Number: 509, 510, 511, 512, 513, 514, 516, 517, 518, 519, 520, 521, 522, 523, 524, 526, 527, 528, 529, 530, 532, 533, 534, 536, 538, 540, 542, 544, 546, 548, 550, 552, 556, 558, 560, 562, 564, 566, 568, 570, 572, 580, 588