Our 6-position dimpling jig is designed to allow you to easily dimple your own barrel. The 6 different, laser-marked spacing sets allow for a variety of gas block applications. The jig will fit perfectly in any bench vise to allow easy dimpling. Spacing is to the center of the 5/32" drill guide holes: .400, .420, .450, .460, .470, and .500. Machined from US Steel and QPQ Heat Treated.Comes with:(1) Alignment set screw(1) Non-marring set screwNOT Included: 5/32" Drill Bit/Spot Drill needed for cutting the dimples.