That is the original design for the glass carrier, and even has to be in the head when using the glassless carrier as the plexi acts as a diffuser. Not sure why the 4 pieces on each corner were put there...the thing actually needs to open to use it (unless you are using the glassless one). Te diffusion/plexi side needs to be up, opposite of how you have it in your thumbnail or else it obviously will not work if a neg. is inside it.
If you have any other ?'s, don't hesitate to ask.
Alexis