Upgrade your Game! Take your BT-4 and give it an authentic military look with the Delta and Delta Elite Upgrade Kits from BT Paintball. 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. You can also convert your BT-4 to look like the BT Delta Elite, including the unique Apex® barrel. Add the Rip Clip® and E-Grip and you’ll complete the Delta Elite package. The Kits contain barrels with shrouds, stocks, magazines, top shrouds and new clamp elbows. 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 and Delta Elite Upgrade Kits from BT Paintball.