The D.B. Smith Field King Professional Backpack Sprayer is chock full of features you'll love and ideal for commercial pest control, orchard and forestry work. Sprayer features a no-leak design using Viton seals and O-rings that keep chemicals off of you. Piston pump. 4-gal. capacity. Weighs 12.9 lb. Field King Professional 4-Gallon Backpack Sprayer