The Big Gator Tools Standard V-DrillGuide 33/64" - 5/8", No. STD3000DGNP, enables users to drill straight every time. It features a 90 degree V-groove design to allow use on corners and round surfaces, and a flat base for use on flat surfaces. The drill guide is easy to use. Simply hold it on the material, clamp, and drill. For use on wood, metal, plastic, and more. It has eight drill hole sizes: 33/64”, 17/32”, 35/64”, 9/16”, 37/64”, 19/32”, 39/64”, and 5/8”. The drill sizes are embedded on top of drill bit guide and the hole alignment marks are permanently embedded on either side of drill bit guide. It's 100 percent U.S.A made.