I posted this photo below, but wanted to repost it here (at the top of the page), so that we focus on the question, "what shall we cal it?".

This is the case-back on an early Carrera. The angled edges allow the screw-back case to be gripped and opened. Mistakenly, I had been calling it a "hex-back" (which is incorrect, as this case-back has 12 sides, whereas a hexagon has six sides).

So what shall we call it? "Polygon-back" is a techinically accurate, and seems good to me, though the phrase is a bit cumbersome. I am guessing that a watchmaker or engineer will be able to tell us what this style of case-opening arrangement is actually called, so until then I am happy with "polygon-back".

Do any readers have different suggestions? Any idea what the correct engineering / technical term might be?

Thanks,

Jeff