"This Hudson Bak-Pak duster sprayer is powered by a gas engine to disperse granular fertilizers and pest control products. Pump Type Duster, Sprayer Type Backpack, Tank Size gal. 3 3/4, Dimensions L x W x H in. 20 x 12 x 28. Portable, flexible, high-efficiency backpack duster 2.4 HP engine 3 3/4-gallon tank Quick adjustable padded shoulder straps and backrest for operator comfort Easily changes from duster to mist blower with two interchangeable tank inserts"