An Airforce One stirrup pump is a high-pressure hand pump designed for filling pre-charged pneumatic (PCP) air rifles and other HPA (high-pressure air) systems. These pumps are powerful, with a maximum working pressure of 300 BAR (around 4350 psi), and feature a four-stage system for more efficient, less effort-intensive pumping. Key features include a built-in pressure gauge, a moisture/oil separator, durable construction, and a stable foot plate for comfortable use.