This versatile kit works with wood and metal interior and exterior doors from 1-3/8'' to 1-3/4'' thick ; The 10-piece kit includes an auto-centering drill guide, anti-splinter depth stop, 2-1/8'' Hole Dozer hole saw, 1'' Hole Dozer hole saw, small arbor & PB, arbor adapter and spacer, two 3/32'' drill bits and two 1/8'' drill bits for pre-drilling holes for latch plate screws ; Bi-metal construction with 8% cobalt for increased wear resistance