I have been saving up to buy a tele-xenar 360mm, and while I was in the US one came up on eBay, but from a non-photographer seller. Since I was in the US and had the minimum bid I went ahead ($162), and no one else bid so I won it. Luckily, everything seems pretty good on it, but it came with a tiny lens board like none I have ever seen before. It is 3" x 3" (76mm) with rounded corners. I have no use for it so thought I would pass it on. Here is is with the 360mm flange still mounted:
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Here it is without the flange:

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And here is the back. It has a little tab sticking out:

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