The Delta Upgrade kit will take your marker from a stock BT-4 and transform it into a complete BT Delta marker, with its authentic submachine gun styling. Add the Rip Clip and E-Grip and you'll complete the Delta Elite package. The Kit contains the barrel with shroud, stock, magazine, top shroud and a new clamping elbow. Begin with a standard BT-4 or any of its variants and modify it into the submachine gun used by Special Forces around the world. Attain the look of real military hardware with the Delta Upgrade Kit from BT Paintball.