The Milwaukee M18 SWITCH TANK 4 Gallon backpack sprayer delivers the industrys 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. The 5 mode pressure adjustment knob adjusts the pressure between 20 to 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.