Gun Sight, Ball Turret, Type K-4 Sperry, B-17, B-24 RAAF and shutter speed is adjustable

and shutter speed is adjustable from 125 to 500

This is the type used on the Douglas A-20 Havoc attack bomber (see photo of instrument location on the A-20 cockpit panel as illustrated in its flight manual) as well as the C-45 Expeditor transport (both aircraft used 2 each)

in its original bakelite case

22317 as used in the WWII-era JU-87 Stuka and JU-88 dive bombers and some ME 110 fighters of the German Luftwaffe

the Consolidated B-24 Liberator

Gun Sight, Ball Turret, Type K-4 Sperry, B-17, B-24 RAAF and shutter speed is adjustableThis is an electro mechanical, automatic Type K 4 Computing Gun Sight used in the Sperry ball turret in WWII era heavy bombers such as the B 17 Flying Fortress and B 24 Liberator. Mounted within the ball turret, it hung from the 'ceiling' of the turret just in front of the forehead of the turret gunner (see illustration from turret manual). The gunner took aim at his target by looking through the glass screen mounted on an optic head the bottom of the