Advantage 1: The specially back removes the plug easily. It’s faster than bi-metal hole saw 2 times. Advantage 2: The specially sharp teeth cuts more smooth, clean . It is more faster than tradition bi-metal hole saw up to 50%. Advantage 3: The carbide grit teeth hardness over 80 HRC.It is more sharp, hard. It’s a longer life in abrasive material. Application: This carbide grit installation light hole saw kit is for 6” recessed light for wood, MDF, drywall, plaster, corn hole board, hardie board, acoustical tile, fiberglass, air brick. Cutting depth: Up to 1” . Package: The carbide grit hole saw Installation light kit includes: 1pcs of 6-3/8" carbide drill bit, 1pcs of 0.43” Hex shank arbor, 2pcs of 0.25”x3.5" HSS pilot drill bits.