This Knapsack Sprayer pump produces a maximum 65 psi and takes only five pumps to reach 45 psi. Features an internal agitator for constant mixing, large fill opening, Santoprene piston cup has excellent chemical resistance for longer life and a high-density UV-resistant poly spray tank with volumeThis Knapsack Sprayer pump produces a maximum 65 psi and takes only five pumps to reach 45 psi. Features an internal agitator for constant mixing, large fill opening, Santoprene piston cup has excellent chemical resistance for longer life and a high-density UV-resistant poly spray tank with volume markings in gallons and liters. It features an internally mounted brass piston pump to eliminate potentially dangerous external leaks markings in gallons and liters.