Thanks, Juan, for the reply. Yes, the sheath does take up all the space in the holder, and it appears obvious that I could use the holders for 3x4 film. Freestyle.com sells Efke 3.25 x 4.25 sheets in a box of 50 for $30. I may give that a try. If I decide to sell them, I'll let you know.
I may be getting ahead of myself a bit, and should stick with film until I get the hang of my camera (and LF in general), ...but does anyone know where I can obtain glass plates to use with these; i.e., when I'm ready for it?
Thanks