The trouble with the different 2 1/4 Negatrans (45 and 23 sizes) is there is rarely any differentiation on the two. They will have no model number, and simply say "Negatrans by Beseler." The model for the 23 does not cover the back of the aperature for the carrier stage on a 45M, leaving over an inch open. So, buying one sight unseen can be a gamble. The 23 model can be used in the 45, but a sturdy piece of light blocking material must be taped to the back, and some registration blocks to center it glued to the frame.
One thing I do not like is that the edge that runs under the transport band is seriously masked out of the available negative print area. This eats up a little over 1/8 of an inch of your negative. Not too swift for those closely cropped scenes...
Although I have the glass platen, I have never used it. Never have had a problem with scratching on films such as fp4, but certainly would not use it for jc/bergger 200 or any other soft, thick emulsion film. For me, this thing is part of my Beseler accessory collection, but was a waste of money for practical work. Just my opinion...