In the 1970s and 80s, Colt offered a 4x20 fixed power scope for its commercial AR (the SP-1). These replaced the earlier 3x scopes, and were designed to fit directly to the rifle's carry handle. They are a simple design, with a duplex reticle, BDC calibrated out to 500 yards in 100 yard increments, and good optics. Well, Brownells found the factory that originally made these scopes for Colt, and they still have the original plans. So Brownells arranged a license to use Colt's name and logo, and had a new run of scopes made. They use the exact same design as originally done, but with material and quality standards of today instead of the 1970s. A pretty cool accessory for a carry handle AR!