The Multi Caliber Collimator (Boresighter) with Arbors is designed for use with pistol and rifle calibers, and helps you get on paper easily without wasting ammo or range time. This boresighter comes in a heavy-duty hard case, with replaceable arbors matching barrels ranging from .177 to .50 cal. This model also includes an adapter for 12, 20, & 28 GA shotguns (will not fit .410 GA shotguns). This version includes shotgun arbors for 12, 20 and 28 ga guns.