This is the Primary (small, 32mm OD) throttle plate for Weber DGV-series carburetors. The Primary throttle is the one that the throttle cable pulls on.
The DGV family of progressive carburetors use a smaller primary throttle coupled indirectly to a larger secondary throttle. This arrangement produced good idle, off-idle, and part-throttle characteristics by running exclusively on the smaller primary throttle. The larger secondary only begins to open when the primary throttle is more than about 50% open.
Fits the primary throttle shaft of Weber 32/36 DGV, DGAV, DGEV, DFV, DFAV, and DFEV; 32/34 DFT; and 32 DIR. Does not fit 38 DGAS/DGES.