The Milwaukee M18™ 4-Gallon Backpack Sprayer w/ SWITCH TANK™ delivers the industry's best pressure control with no manual pumping and an interchangeable tank design. Designed to meet the needs of professional landscape maintenance, the battery-powered backpack sprayer provides instant, constant, and adjustable pressure up to 140 PSI and a 24 ft vertical spray distance. The 5-mode flow rate knob adjusts the flow by 0.1 – 0.52 GPM, giving you the capability to complete a wide range of applications. The Milwaukee M18™ REDLITHIUM™ XC3.0 Battery (sold separately) provides you with up to 20 tanks of spraying per charge (on Mode 3). The 4-Gallon Sprayer Tank Assembly features a dual diaphragm pump for longer pump life and Viton® seals for increased durability against harsh chemicals. The sprayer tank has an optimized design for better weight distribution, a wide mouth opening for easier pouring, and a strainer that filters debris from getting into the tank. The backpack frame includes padded straps, lumbar support, and a hip belt, giving you added comfort during extended spraying applications. The 4-Gallon Sprayer is made up of two components – the M18™ Powered Base and the 4-Gallon 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 spraying applications, eliminating cross-chemical contamination. The Powered Base is compatible with the 4-Gallon Water Supply Tank Assembly (49-16-19WS).