The Dawson Light Speed Rail adapter was the heat back in 2004-2006 or so, prior to the real proliferation of Picatinny rail framed 1911s, and with many owners still owning legacy format Government Models that needed to catch up with the developing weapon mounted light trend. The rail required a proprietary adapter to be attached to the light (Nitrolon, Military Light, and X200/X300). The modified frame without an attached light would fit into certain 1911 holsters with minimal alterations. It seemed like the ideal setup, and our 10-8 signature 1911 with Nighthawk featured this rail.
Fast forward to present day, and every vendor sells a rail frame 1911, and Dawson has discontinued the Light Speed Rail. With the current state of the market, the lack of continuing holster support (the growth of tightly molded pancake style Kydex holsters meant that fewer and fewer holsters would “also fit” the Dawson Rail), and the need to semi-permanently alter the light (only one light is left compatible with existing adapters – the Surefire X300) have pretty much left the Dawson Rail as an interesting relic of a bygone era.