The Milwaukee M18 SWITCH TANK 4-Gallon Backpack Concrete Sprayer Kit (2820-21CS) delivers the industry’s first interchangeable tank design with no manual pumping. Designed to meet the needs of concrete contractors, the battery-powered concrete sprayer delivers instant, constant and adjustable pressure up to 120 PSI and a 25 ft spray distance. The 5-mode pressure adjustment knob allows you to adjust the pressure between 20 – 120 PSI, delivering the capability to complete a wide range of applications. The M18 REDLITHIUM XC3.0 Battery provides you with up to 12 tanks of spraying per charge. The 4-Gallon Concrete Sprayer Tank Assembly features a dual diaphragm pump for longer pump life and Viton seals for increased durability against harsh chemicals. 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 giving you added comfort during extended spraying applications and a handle for convenient transport and storage. The 4-Gallon Concrete Sprayer is made up of two components – the M18 SWITCH TANK Powered Base and the SWITCH TANK 4-Gallon Concrete Sprayer Tank Assembly. The Powered Base includes the motor, battery compartment, and REDLINK electronics while the interchangeable Tank Assembly includes the pump, hose, and wand. The isolated pump, hose, and wand 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 sprayer. The Powered Base is also compatible with SWITCH TANK 4-Gallon Sprayer (49-16-28PS) and 4-Gallon Water Supply (49-16-28WS) Tank Assemblies. Our M18 SWITCH TANK 4-Gallon Backpack Concrete Sprayer is part of the M18 system which is fully compatible with over 175 tools.