I have a 120 (6x9) film rollback for a Graflex RB Series D 3.25 x 4.25 camera. It is labeled Graflex "23". I see on eBay what looks like an identical rollback, except it is labeled Graflex "22". Could someone tell me the difference in the "23" and "22".

If complete a 22 Graflex roll back would fit a Graflex back and give 12 2 1/4x2 1/4 images. So make sure the counter does go up to 12.

Also a picture of the film side of either of the '22" and "23" backs with the dark slide in, will look the same. It's only when you remove the darkslide that you'll see the mask on the "22"

And for other readers a "22Graflex" or 23 Graflex will fit a Graflex back, "23 Graphic " fits a Graphic or Graflok back.

The number is the (approximate) size of the negative in inches (made back in ancient pre-metric times): 22 makes a 2x2-inch negative, and the 23 is about 2x3.

22 = standard 6cm (2.25") square negative, like most 120 cameras make.