Thought I'd better post this image as well. I do know what the stamp represents, it's the size I'm inquiring about. This image came from an eBay auction, not mine. The stamps below and to the right are the same stamp in standard size. My Michel does not list the oversized stamp and somewhere I've seen this listed as a proof or essay?
APS Member #192156 GPS Member #9722 Member INFLA-Berlin