Are you tired of your drill bit waking, wander or drifting off center on round materials? BIG GATOR TOOLS' BGT V-Drill 3 Pack V-Drill Guides (2 Standard Imperial Fractions (SAE) and 1 Metric Sizes) is like a portable drill press for precision drill bit alignment! The precisely milled V-groove along the bottom of the drill guide allows for perpendicular alignment with all drill sizes on round parts like pipes, dowels, and outside corners. Bottom surface is precision ground to assure stability and accurate perpendicular alignment on flat surfaces. The flat side allow 90° drilling into flat surfaces-just clamp and drill. Engineered to be the most universal tap guides ever! STD2000DGNP Portable V-DrillGuide w/9 Standard Imperial Fractions (SAE) Size: 13/8, 25/64, 13/32, 27/64, 7/16, 29/64, 15/32, 31/64, 1/2. STD1000DGNP Drill guide is sized for Standard Imperial Fractions (SAE) drill bit sizes of 3/8" drill index—everything from 1/8" to 3/8" in 1/64" increments. 17 SAE hole sizes to work with. Guides are made from special nickel alloyed steel that is heat treated for durability. MDG1000NP Metric drill guide is sized for 17 drill sizes: 3, 3.3, 3.5, 4, 4.2, 4.5, 5, 5.5, 6, 6.5, 6.8, 7, 7.5, 8, 8.5, 9, 9.5mm. A great addition to anyone's tool set! Drill Straight - Every Time! Made in the USA.