ATN uses the purest grades of heavy glass and computer aided optical designs. All lenses are multi-element, high aperture and multi coated. Night vision devices utilize only the best hand selected Image Intensifier Tubes. Material range from titanium, aircraft quality aluminum to hi-impact plastic. All unit feature O-rings, nitrogen purging and hard exterior coating. The Ultra Sight can be mounted in place of the handgun's rear site with the help of the USDC bracket. For use with Sig Sauer 220, 226, 225, 228, 229, 245 and P226. For all warranty claims, please contact ATN Warranty center directly at 1-800-910-2862 for repair or replacement. Non Returnable to Cheaper Than Dirt!