The U.S. Navy Adjustable Reflector Mark 4 Mod 0 was an adjustable gunsight head attached to the Mark 8 illuminated reflector gunsight. It was primarily used on world War 2 Aircraft such as , Douglas A-26 / B-26 Invader, Lockheed P2V Neptune, Grumman  F4F Wildcat ,Grumman  F6F Hellcat , Grumman TBM Avenger and some were on the  Republic P47 thunderbolt. This mark 4 mod 0 sight came out of a F6F Hellcat that we were using for parts to repair another airplane that I was working on about 20 years ago. It has a Mark 8 Mod 8 Illumination Sight adapter on it and the original 24 volt  bulb still works also included is the anti vibration mount and upper sight level. I was going to make a desk mount for it but never did and decided to sell it instead so another collector could enjoy this piece of WW2 history .  The pictures of the sight illuminated is a little off due to me shaking and trying to get a good picture.