Greetings! I recently purchased an Avus that came with an assortment of old items including three film holders, a pack film holder, and a ground glass. Unfortunately they don't fit the Avus! Needless to say, they don't fit anything I have. Outside measurements are 3 5/8" x 5 3/16" for the ground glass with the holders only slightly longer. Are these for a 9x12? Anyone have ideas on where/how to locate holders for the Avus? Thanks!