Integrated rail integration, tighter build quality, inner threaded barrel, mock suppressor included, and double tactical light upgrade! The WellFire M4 TacSpec has an enhance spring fueling its high power. The rifles endless M4 S-System integrated railing allows for any customized configuration its user can think up! Other features are: fixed hop up, customizable 4-position rear stock, sling mounts, front sight, adjustable / removable Tac grip!