The Milwaukee M18 SWITCH TANK 4-Gallon Backpack Water Supply Kit (2820-21WS) delivers the industry’s first interchangeable tank design with no manual pumping. Designed to meet your water supply needs for concrete cutting and coring, the battery-powered water supply delivers instant, constant and adjustable pressure up to 60 PSI. The 5-mode pressure regulator adjustment knob adjusts the pressure between 20 – 60 PSI for ultimate control. The M18 REDLITHIUM XC3.0 Battery provides you with up to 12 tanks of water delivery per charge. The 4-gallon water supply tank features a dual diaphragm pump for increased durability and longer pump life. The tank also has a wide mouth opening for easier pouring and a strainer that filters debris from getting into the tank. The backpack frame includes wide straps and a handle providing you with convenient transportation and storage. The 4-Gallon Water Supply is made up of two components – the M18 SWITCH TANK Powered Base and the SWITCH TANK 4-Gallon Water Supply Tank Assembly. The Powered Base includes the motor, battery compartment, and REDLINK electronics, while the interchangeable Tank Assembly includes the pump, 10ft hose, and quick-connect. The isolated pump, hose, and quick-connect design allows you to add on tank assemblies for different applications, eliminating cross-chemical contamination. It also provides you with the ability to replace the tank assembly at a lower cost of ownership compared to replacing the entire water supply. The Powered Base is also compatible with the SWITCH TANK 4-Gallon Concrete Sprayer (49-16-28CS) and 4-Gallon Sprayer (49-16-28PS) Tank Assemblies. The M18 SWITCH TANK 4-Gallon Backpack Water Supply is part of the M18 system which is fully compatible with over 175 tools.