These headspace gauge sets will allow you to determine the headspace on your .22 LR firearm. Each gauge is marked with its size. Use these to check existing firearms, when installing prefit barrels, or along with Shim Kits to fine-tune headspace to match your ammunition. Headspace gauges are made from stainless steel. The 3-D printed storage box is included. 3 set options available. Select which one you want. 7 gauges from .039″ to .045″ 7 gauges from .046″-.052″. A complete set 14 gauges from .039″-.052″ you can buy individual gauges here