Mark, If you look at the picture in the RB of the 3127 you will see that the edges of each segment on the side has a flattened separator where the 2127 has the "sharp" edge on the sides of each segment. I hope this makes sense but if you look closely at the two pictures, here and the red book, I think you will see what I'm referring to. I wonder if the 2127 had an issue with the strength of the edges where the flats meet and they went to the flattened edges on the side of each segment? Maybe just aesthetics with the flattened edges being sort of accents. Beats me.
Harry