West German (Bundeswehr) Y-harness for webbing gear (German: koppeltragegestell).. These were attached to a belt to keep the belt at the waist, and to attach field gear to.
Taking advantage of their Cold War, mechanical appearance, European costume makers like Nuclear Snail, Wasteland Pirate, etc have used them as raw materials, taking them apart and using the straps and the clips to add texture to their creations.
Type A suspenders refer to the more common style, which has boxy, rectangular clips at the ends of the straps.
Type B suspenders refer to the more rare style, which has long, flat, hinged clips.