The RC Allen directional gyro provides accurate heading information through 85 degrees of pitch and roll, 360 degrees in yaw. Quick recovery times even after violent maneuvers. Caging knob resets the gyro to magnetic compass. Fits standard 3 1/8" panel opening. 6 5/8" long. Vacuum Gyro requires 4-6 in. Hg. vacuum source for operation. Ship Weight 4 Lbs. Meets FAA TSO-C5c.