SOLO® 475-B 4GAL 4 gal Diaphragm Pump Backpack Sprayer, Bleach Resistant. Built for comfort, built for convenience and built to last. SOLO's ergonomic design contours to your back for greater comfort. A low number of wearing parts and sturdy technology ensure a long service life and minimum maintenance. The large filling aperture for convenient filling of the tank and smooth-running pump make spraying pleasant work. The SOLO® 475-B is capable of producing up to 60 PSI, with its rugged connecting-rod-actuated diaphragm pump. The diaphragm is made of top quality material for its resistance to harsh chemicals and its long life expectancy. Designed with the ability to pass small abrasive particles without damage to the pump assembly. The diaphragm pump is ideal for handling chemicals in wettable powder form, as well as liquid formulations.