The Peerless PRG Precision Gear Projector Mount is changing the way image alignment is done. The patent-pending precision gear design provides exact tilt and roll image positioning with a simple turn of a knob. Once the installer sets the precision gear to the desired position it stays securely in place. It will not shift during projector maintenance, bulb replacement, and will not loosen or change alignment due to vibration, accidental bumping etc. What's real nice is that you don't have to hold the projector up while making the adjustments. With Peerless' PRG Precision Gear Projector Mount the installer sets and forgets.