Is it part of a flashgun assembly? The only name I can track down is VACUB.
Yes, it is the sync mechanism that trips the flash-gun (blitzlicht).
There's another element: a replacement shutter-speeds dial with a little finger on the edge to trip the reed-switch in the VACU.
I think there were two basic versions, one for bulb sync, the other for strobe (electronic flash).
The little wave-symbol inside the oval indicates which version this is , but I don't remember which symbol is for which.
The earliest Leitz flash guns are the most elaborate and nifty, in my opinion: they consisted of a replacement baseplate with the flash contacts incorporated(SELSYS?), then a bracket the wrapped around the end of the camera, to which the battery tube clamped, then the dish-reflector sliped into a stirrup strap behind bulb socket (Edison screw-base, with an adapter stub to bayonet base which positioned the smaller bulb at the optical center of the reflector dish). I got one in a "goody box" of Leica sundries from KEH a long time ago. Mine seems to be from the 1930's the battery tube is black lacquer, and the bright bits are nickel.
I have actually used it.
😀
I would love to get the various VACU sync gizmos for my later LTMs.
I also have a GeissKontackt add-on flash sync.