https://upload.wikimedia.org/wikipedia/commons/thumb/f/f7/KIT-1A-Mark_XV_Identification_Friend_or_Foe_%28IFF%29_-_National_Cryptologic_Museum_-_DSC07993.JPG/88px-KIT-1A-Mark_XV_Identification_Friend_or_Foe_%28IFF%29_-_National_Cryptologic_Museum_-_DSC07993.JPG