The Backbone Rail from AirMarksman is more than just an extended optics rail. The Backbone Rail has been designed to tie your entire rifle together and eliminate tolerance stacking by replacing both the factory optics rail as well as the factory backbone plate with one piece of extra rigid aircraft-grade aluminum. The AirMarksman Backbone Rail drastically reduces flex in the entire rifle, creating a more anchored and consistent shooting platform at the cost of only 4 added ounces to the total weight of the rifle. On top of stiffening the FX Impact platform, the Backbone Rail adds extra Picatinny rail, the most useable rail space of any rail system on the market, with 30 MOA of elevation milled into the rail. Based on input from top NRL Airgun Class shooters, AirMarksman also added a bolt retention detent to the Backbone rail that keeps the cocking handle and bolt probe held in the rear position when it is opened. This feature prevents accidental double feeds and removes play in the cocking handle. The bolt retention detent can easily be removed during the installation process if shooters are looking to maintain the factory cocking handle feel. 100% made in the USA, the AirMarksman Backbone Rail System is the ultimate precision top rail for the FX Impact Platform.