This is an original  Military Fighter Aircraft Radar Altimeter Type ID 950/APN-150(V) Gauge Instrument. 

It is 3 1/4 x 3 1/4 x 6 inches. 

The radar altimeter tells the pilot exactly how high they are over the ground when they are near the ground. It is used for low level navigation and for instrument approaches. **This item is being sold as a collectable or for parts only.**