U.S. Navy Bureau of Ordnance A.A. Range Indicator. Bakelite 5" diameter with 1.75" center hole having moveable wires for ranging; handle at the bottom for gripping. Face has orange text with different aircraft types, white numbers indicate range. For use on board ship bu anti-aircraft gun crews. Center ring was rotated to attacking aircraft wingspan and aircraft identified, then white numbers gave range. Reverse has data plate and text cast in Bakelite: "To be held 24 inches from eye". Very good, fully functional.