I installed the XS on my Glock 23 and shot 100 rounds today to find that the elevation is 6' low at 10 feet and over a foot low at 12'. The Warren sights I removed were accurate. The elevation cannot be adjusted on the XS. They are relatively cheap for a night sight and now I know why. The guy shooting 100 yards on You Tube with XS sights wasn't shooting this crap.