The AR264 arbor is used in conjunction with Aimshot .223 Laser Bore Sight. It is made of 100% brass for quality and durability. This arbor is used for all of the following calibers: - 264 Win, 300 Win, 7mm Mag, 300 Weatherby, 270 Weatherby, 7mm Weatherby, 340 Weatherby, 257 Weatherby, 8mm, .358 Norma Mag, .308 Norma Mag, .416 Rem Mag, 7mm Shooting Times Westerner