The Big Gator Tools Metric V-DrillGuide is designed to allow users to have the precision of a drill press without losing the accuracy. The innovative 90-degree "V-groove" found on the entire bottom of the drill guide helps ensure perpendicular alignment on round and cornered material. To use this tool, hold the drill guide on the material, clamp, and drill. It can be used on various surfaces. The V-DrillGuide has nine holes that are heat-treated to prevent wearing out. The hole sizes and hole alignment marks are permanently embedded onto the guide. The holes are sizes: 10mm, 10.5mm, 11mm, 11.5mm, 12mm, 12.5mm, 13mm, 13.5mm, and 14mm. Standard sizes are also available. All V-DrillGuides carry a lifetime warranty and are 100 percent USA made.