There are no masks to restrict other formats, since I was only interested in 6x17. They are easy to make from plastic cards. For Sinar Linhof Wista Horseman Toyo.
The item "DAYI Multi-Format 6x9 6x12 6x17 Roll Film Back For 4x5 Large Format Camera" is in sale since Saturday, September 11, 2021. This item is in the category "Cameras & Photo\Film Photography\Film Backs & Holders". The seller is "yeolde" and is located in Saint-Petersburg.This item can be shipped worldwide.