This is our latest design for the SP-445 film holders for 4x5 sheet film. Each film holder holds two sheets; comes in a set of two.
Here's the backstory: we've been fighting production problems with the current design of the film holders (rev 3). The “thinness” of the plastic causes some of them to warp when ejected from the mold; forcing us to discard way too many parts!
Taking one of the lessons learned while testing the SP-8x10+ tray system, we've added texture to the face of the holders. The texture breaks the surface tension and keeps the film from sticking while letting us to increase the base thickness, eliminating our warping problem.
If you're happy with your Rev 3 film holders, there's really no reason to change.
Note: due to the thicker plastic, you'll get away with slightly less liquid in the tank, 450 ml.