The remote directional gyro provides accurate heading reference & stabilization for the Sandel SN3308 EHSI system. The model 4305 features a high inertia, long-life gyro spin motor and oversize gimbal bearing that withstand high vibration environments. It is conservatively rated at 8,000hrs MTBF (Mean Time Between Failures). Features integral spin motor speed sensor sensor that detects true rotation speed for use with failure warning devices & system diagnostics.Certified to FAA TSO C5c, the unit is approved to 55,000 ft. & available in either a 28V or 14V version.