I use a 4x5 film holder very similar to this one. Mine was apparently made in the 70's by phototherm (according to the guy I bought it from). It is made of stainless steel and fits in a standard 4 roll stainless steel developing tank. It must not have been a very big seller because it is the only one I have ever seen. The concept is pretty much exactly the same as this one (3 sheets bowed out on each side) - but the execution is a bit different. Long story short, I am very happy with the results I am getting from the phototherm (my only gripe with it is loading - but the plastic one this guy is selling looks like it would be easier to load). I imagine that this fellow's contraption would offer similar results. In any case it is a very nice alternative to the leaky square tanks or the extremely overpriced 4x5 Nikors if you want to do some daylight developing of 4x5 film.