I just received a shipment today, and now have the Argentum contact printing frames in stock in the banquet sizes. The actual image areas are:
25x56cm (9.8" x 22") for 7x17 and 8x20
36x56cm (14.1"x22") for 12x20
I can also confirm that backs of the banquet frames are three piece (two hinges) with three springs - as requested.
I have another shipment on the way that will include the standard size frames:
24x30cm nominal (25x31cm = 9.8" x 12.2" actual)
30x40cm nominal (31x41cm = 12.2" x 16.1" actual)
That shipment should be arriving in about 7 - 10 days.
I'll try to post some photos of the banquet format contact printing frames this weekend.
Really Big Cameras