I just got a polaroid back for my 4x5 Speed Graphic on ebay, it's a roll film back and has its own focusing groundglass set up. I guess I thought this was a pack film back, not roll. Can anyone tell me what model back this is and if there is any film available for it?

I can't remember the models off hand, nor the number films it took. Something like 47 or so.

What you've got is a nice collector's piece. Film hasn't been made for it in years and years...