The device is a hand-operated tool attached to the multi-piece rim/wheel and permits the tire technician to push and hold the front rim flange and bead of the tire back to install the O-Ring. The tool is adjustable and works on all OTR/EM tire and wheels up to 30 inches in diameter. The tool also eliminates the danger of pushing the heavy equipment off the lifting jacks if a tire crane is being used to push the flange and bead back. www.esco.net