Al, I just mounted mine on a lens board and put it on my 8X10 and it will not cover the format at infinity (I just look through the cut-out corners of the ground glass and can't see through the lens from the corners). Wonder if they made different versions. I have a 5X7 back that I plan on using it with.
How can you tell the different sizes of the Alphax shutters? I am watching a few on ebay but there is no size indicated, so I don't know what they are. I guess I could ask the seller for measurements.