Big Gator Tools STD Series 3PC V-Drill Guide w/35 SAE Hole Sizes 1/8" - 5/8" 3PC Set Includes: (1) STD500NP, (1) STD1000DGNP & (1) STD2000DGNP Special nickel alloyed steel heat treated for durability. Non-plated material with light oil coating to prevent rust. Centers the holes on pipes, dowels & outside corners. Flat side allow 90 drilling into flat surfaces-just clamp and drill. Automatically squares up the drill with the surface. Alignment marks on both sides, to line up on center. Bottom surface is precision ground to ensure stability & accurate perpendicular alignment on flat surfaces. Round stock hole alignment marks on one side. Prevents drill bit wander. Portable, pocket-sized and housed in a handy plastic storage case w/surface ridges to prevent opening, PegBoard-Friendly.