This is a reliable all-purpose Sprayer in back pack form. With lumbar support and thickly padded shoulder straps, the BP4 has the features of the best back packs. Sprayer has 4-gallon capacity, internal piston pump for dependibility, durable Viton seals, external pressure adjustment, and adjustable pump piston seal to guard against leaks. Adjustable pump handle makes it easy to pressurize the tank while on the move. Telescoping wand has a fixed fan spray tip and an adjustable cone-to-solid-stream tip for a variety of uses. Spray Doc Back Pack Sprayer weighs 10 lbs.