Solo 4.5 gallon backpack sprayer with its connecting rod activated piston pump is capable of producing a wide pressure range up to 90 psi, (optional plug required to obtain 90 psi), performing virtually every spraying task. Easily and effectively handles disinfectants, fertilizers, herbicides, pesticides, and formulations for tree, shrub and plant protection (clean sprayer between uses). The rugged high-density polyethylene tank and internal Viton seals insure long life and durability.