Professional 4-gallon backpack sprayers are individually water-tested at the factory, ensuring the lowest defect and return rate in the industry! High pressure sprayers feature a UV-resistant, polyethylene tank marked in U.S. gallons, Imperial gallons and liters. Other features include large, easy-fill, 6 tank opening with built-in check valve in the lid to prevent spills, ergonomically-designed pump handle which rotates to upright storage position for easy transporting, long-life spray pistol with brass shut-off pin and double O rings, and aluminum or brass wand. May be used for herbicides, insecticides, fungicides, fertilizers, stains, sealers, oil-based products, and solvent-based products. Should not be used with acids.This multi-purpose sprayer features a patented diaphragm pump that is capable of two million strokes without leaking (equal to over two years of constant use). The diaphragm pump is designed so that there is no friction between moving parts and no nuts or bolts to tighten or adjust, thereby eliminating leaks from worn out O-rings or gaskets or loose nuts and bolts. In addition, each tamperproof pump is sealed at the factory and then tested to 70 psi before being installed. The diaphragm pump has a working pressure of 15 to 60 psi and a maximum pressure of 70 psi. Other features include a 20 brass wand; 51 industrial hose; stainless steel pump handle, base, lever, and hardware; tank treated with UV inhibitors; lid with raised carrying handle; wand clips; adjustable padded shoulder straps; adjustable brass nozzle; fan nozzle; and chemical-resistant O-rings and seals. The sprayer's pump module is repairable.