The sight comes with two bulbs in the mount. I was at the National Museum of the USAF in Dayton Ohio and I saw this sight with the F-86A Sabre Jet. The F-86A was one of the first jet fighters and was very successful during the Korean War against the MIG-15. This sight was also used in the top turret of the PB4Y-2 and the P2V Neptune.
It was displayed in the New England Air Museum as having been used in the F-4U-7 Corsair and the F-9 Panther. It was also used by the French flying the F4U-7 Corsair. This sight is 5 x 6 1/2 x 10 inches and weighs just under 8 pounds. The item "Korean War USAF F-86A Sabre Jet Fighter Aircraft Pilots Mark 18 Gun Sight" is in sale since Thursday, December 21, 2017. This item is in the category "Collectibles\Militaria\WW II (1939-45)\Original Period Items\United States\Field Gear, Equipment".The seller is "dauntlessaviation" and is located in Apache Junction, Arizona. This item can be shipped worldwide.