Featuring a chambered design, the Pressure Over Drive is ideal for seating even the most stubborn tubeless tires The secondary chamber can be pumped up to a pressure enabling a stainless steel foot-lever to release the compressed air in an immediate, continuous discharge, quickly and easily seating the tire bead Features a durable steel and aluminum construction paired with a highly accurate and precise analog pressure gauge An extra long, nylon-reinforced beaded hose terminates in Presta and Schrader compatible ABS-1 Pro chuck offers plenty of versatility When using as a regular pump, you must fill the air chamber before air will begin to flow into empty tire/tube. When topping off a tire/tube that already has pressure in it, the chamber will have to reach the same pressure the tire/tube is at first before it will begin to inflate it further.. FLOOR PUMP OVERDRIVE