Achieve a clear view of game far off in the distance by mounting the SSI Site-Rite .17 HMR Chamber Cartridge Red Dot Boresighter on your firearm. Designed for 0.17 Hornady Magnum Rimfire (HMR) cartridges, this laser boresighter features a red-dot reticle for visibility during dark early-morning or late-night hunts and an external on/off switch for easy operation. 30-yard sight range. 3.5" dot size at 100 yards.