Roberto -

You don't want the "rollfilm holders for sliding back" - those use the 2x3 Graflok fitting. But there are still two different kinds of Wista rollfilm holder for 4x5 - the "45" type backs which attach to any camera with "international style" or "Graflok style" clips, and the "Field 45" type which has "butterfly wings" on the back which are intended to allow it to be used as a slide-in holder as well. What I don't know is whether the backs on the Wista metal field cameras open far enough to allow use of these "Field 45" slide-in types. Does anyone else here have any experience with this combination?