The StratoLauncher IV Deluxe Upgrade Kit is comprised of 3 components: air pressure gauge, tilting ball head, and metal Q-Release hose connector. Installing this kit on the standard StratoLauncher IV model will upgrade it to our StratoLauncher IV Deluxe model, which will give you additional benefits from these enhancements. The large 2-inch face stainless steel air pressure gauge is easy to read, indicating pressures from 0-160 PSI. Max recommended air pressure is 120 PSI when used with the StratoLauncher IV and a typical PET soda bottle rocket. The tilting ball head serves a twofold purpose: 1) minimize drift by slightly launching into the wind and 2) enable vertical launching by adjusting for sloped terrain. Finally, the metal Q-Release hose connector is durable and efficient for thousands of water rocket launches.