The Barska Bore Sight with 15 Fixed Arbors uses a 15 piece arbor set that ensures precise bullet placement from the get go. The boresighter fits snugly in the rifle barrel to eliminate any "play" that can result in an inaccurate boresighting adjustment and poor shooting accuracy.FeaturesArbor studs caliber: 0.177, 0.22, 6mm, .25, 6.5mm, .27, 7mm, .30, .32, .338, .35, .375, .44, .45Type: iron