This 126 Film Negative Mask Set fits the Omega Negative Carrier Holder D-size for use in the Omega D5500 Enlargers, and C-size mask sets up to 4 x 5".
The mask set and the carrier are part of Omega's instant change negative carrier system, which allows you to switch out negative carriers in a quicker manor saving you time in the darkroom.
I bought this to use with my Nikon D850 and 60mm macro to image some old family color and BW 126 negatives. It took me a bit to get the negatives properly oriented between the two plates (having a bright back light and black negative holder complicated matters) and but once I figured that out, these plates held the 126 negatives flat (with a little pressure from me) and I'm happy with the images.