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 Smith & Wesson Sigma 9C, 9F, 40C, 40F and 40V. 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!