Milwaukee M18 SWITCH TANK 4 Gal. Cordless Backpack Sprayer (Tool Only)Interchangeable tanks, no manual pumping Add on and interchange tank assembly to eliminate cross chemical contamination Replaceable tank assembly delivers lower cost of ownership Instant, constant and adjustable pressure for ultimate control Up to 120 PSI & 25 Ft. spray distance Run time up to 12 tanks per charge with M18 REDLITHIUM XC3. 0 battery Critical seals: Viton for increased durability against chemicals Dual diaphragm pump for longer pump life