Guys, I got a glass 4x5 negative carrier w. my D5 enlarger. In fact, it looks like this one I found on Ebay:

Not sure if it's AN glass or not, but it does look identical, and the edge of one of the glass sheets is 45deg tapered cut. Is this AN glass?? How perfect does the glass have to be? It has no scratches that I can see, but it does have just a few, very small specs that wont' come off in cleaning. So just trying to get an idea if this is usable. Also, is using a glassed neg. carrier Mandatory for flat negatives=sharp prints?? I certainly cannot afford a new carrier from Calumet above ($200).