oh, I forgot to mention that I am having trouble identifying what format these negative carriers will service. Any ideas?

2013-05-07 10.16.59.jpg 2013-05-07 10.17.18 HDR.jpg

I'm also pretty sure that this is a 4x5 negative carrier, but I think it's missing a piece of glass since there is a gap between the two contacts:2013-05-07 10.17.46 HDR.jpg