The Milwaukee® M18™ SWITCH TANK™ 4 Gallon backpack sprayer delivers the industry's first interchangeable tank design with no manual pumping. Designed to meet the needs of professional landscape maintenance, the battery-powered backpack sprayer delivers instant, constant and adjustable pressure up to 120 PSI and a 25 ft spray distance. The 5-mode pressure adjustment knob adjusts the pressure between 20 - 120 PSI for a wide range of applications. The M18™ REDLITHIUM™ XC3.0 battery (sold separately) provides up to 12 tanks of spraying per charge. The sprayer has a dual diaphragm pump for longer pump life and Viton® seals for increased durability against harsh chemicals. The sprayer tank has a wide mouth opening for easier pouring and a strainer that filters debris from getting into the tank. The backpack frame has wide straps for added comfort during extended spraying applications and a handle for convenient transport and storage. The 4 Gallon sprayer is made up of two components - the M18™ SWITCH TANK™ powered base and the SWITCH TANK™ 4 Gallon sprayer tank assembly. The powered base includes the motor, battery compartment, and REDLINK™ electronics. The interchangeable tank assembly includes the pump, hose, and wand. The isolated pump, hose, and wand design allow different tank assemblies to be added for different spraying applications, eliminating cross-chemical contamination. It also allows the tank assembly to be replaced at a lower cost of ownership compared to replacing the entire sprayer. The powered base is compatible with the SWITCH TANK™ 4 Gallon concrete sprayer (49-16-28CS) and 4 Gallon water supply (49-16-28WS) tank assemblies. The M18™ SWITCH TANK™ 4 Gallon backpack sprayer is part of the M18™ system which is fully compatible with over 175 tools.