Space Age AV32+2DCD Category : Space Age Electronics That is an electromechanical horn on the rear of the strobe plate.
EST 882-2B Category : EST/EdwardsThis unit has an electronic horn rather than an electromechanical mechanism.
Wheelock ET-1080-WS-24 Category : WheelockYou can’t really tell from the pictures, but the strobe is practically falling out of this particular unit.