Solo 4 gallon Backpack Sprayer | Solo Backpack Prayer 4 gal CapacitySolo 4 Gallon Backpack Sprayer Solo Backpack Prayer 4 Gallon Capacity Now with a piston pump, operated by a maximum leverage pump handle, which can be mounted on either side of the tank. Pump chamber holds pressure, so minimum pumping effort will produce consistent back pack sprayer pressure (maximum pressure is 90 psi) for a wide range of spraying tasks. 4 Gallon Solo Backpack Sprayer Features: High impact, UV resistant polyethylene tank is made for