Description The MILWAUKEE 2820-21WS M18™ SWITCH TANK™ 4 Gallon backpack water supply kit is the industry’s first interchangeable tank design with no manual pumping. Designed to meet 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 adjustment knob adjusts the pressure between 20 – 60 PSI for ultimate control. The M18™ REDLITHIUM™ XC3.0 battery provides up to 12 tanks of water delivery per charge. The MILWAUKEE 2820-21WS 4 Gallon water supply tank assembly has 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 for 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.