The Big Gator Tools Large Standard V-DrillGuides are offered in standard and metric sizes. V-DrillGuides are manufactured from special heat-treated nickel-alloyed steel for durability and longevity. The V-DrillGuides feature a precision ground base to assure stability and accurate perpendicular alignment of drill bits on flat surfaces. The V-groove allows for perpendicular alignment of drill bits on round and square cornered materials. Large Standard V-DrillGuide drill sizes include: 3/8”, 25/64”, 13/32”, 27/64”, 7/16”, 29/64”, 15/32”, 31/64” and 1/2”.