Optical collimators save you time and ammunition by getting your rifle or handgun “on paper” without firing a shot. Gives hunters, target shooters, and gunsmiths the convenience of initial sighting-in of scopes and sights at home or in the shop. Easy-to-use: attach collimator to the muzzle, then adjust the windage and elevation of the scope or iron sights until they align with the collimator grid. Sights centered on the grid will shoot very close to point-of-aim at 100 yards. Collimator is CNC-machined from aluminum, then hardcoat anodized to protect the finish from nicks, dings, and surface wear. Includes convenient carrying case that protects from damage and keeps each item clean and ready to use. Standard model features 15 steel arbors that fit bores ranging from .177 to .50 caliber, including popular metric calibers, to provide precise alignment with the collimator for extremely accurate sight adjustment. Roll-up storage case easily fits in your range bag or tool box.