Hello, back again with this new images from the ebay seller:

I don't know what that thing is but I wouldn't buy it. For any price.

I have to agree. It does not have the sliding chrome retaining bars necessary to hold the rollfilm adapter, or other "Graflok" accessory, into the back. The focusing panel illustrated earlier looks right, but this frame is very strange.

It looks like the part that would attach to the back of a body but what body is a mystery.

Right. For one thing, the four holes for the fasteners should be above and below the rails, if it's to mate with a miniature "Speed" (or "Crown") -- the holes on this one are on the ends. The light trap looks right for "Graphic" holders, but the absence of the sliding retainers (or, as far as I can see, anywhere to attach them) would limit its use to double-sided cutfilm holders.

Martin: if you haven't aready done so, it would be worth your while to go to the "FAQ" section of this site and find the entry that describes the "Graflok" back (and other backs). The two illustrations, though small and showing a 4x5 back, will give you a good idea of what you're looking for. You'll notice that the "Graflok" back should come with a fold-down rear sight, and should have two sliders, above and below the focusing panel. These are what holds rollfilm adapters and other things in place, when you've removed the focusing panel.

The very next entry on that page shows a "Graphic" back, which is what you have now. Yours seems to be a late model; it is a lot more sophisticated than the one on my "Anniversary Speed."

Dudes, I thank you a lot for your support; so I on one side I "keep on seekin" in ebay, and on the other side I think about conversion of my back, but in another way as described on this site, I wonder how to fix it not top and bottom but left and right side.^^
the drawback of an european residence is that Graflex stuff is mostly sold in ebay US and shipping fees and costs for money transfer are painful^^,
So thanks to all of you and have a nice time and a proper light.^^

Somewhere on this site some years back I read that a special strap retainer was made for this camera/roll film holder.

Digimassa,
If you remove the focus panel, cut the edge of a large outer diamater flat washer or fabricate a flat piece of metal to fit over the spring mount without protruding into the holder rail area and using said piece of metal/washer and a screw and attach a length of velcro/hook and loop fastner on each side then either different halfs of the fastner on each side and pull tight over roll film holder when in place to secure it or use the same half on both sides and glue patches of the opposite to the back of the outer shell of the roll film holder to secure it.
A leather strap with a buckle to work like a belt can be used and mounted in the same manner.