I've made a small adjustment to the Commercial frames which should work just as well in an National deep (brood) box.
I took an old National brood frame and removed the two bars which are set at the bottom. These are 6mm x 8mm x 360mm. I cut them into 4 equal 90mm lengths. I glued and nailed these to the sides of the top bars. I made these adjustments to 3 of the frames.
The result is that the frames are spaced at 12mm apart instead of 8mm. The Commercial box fits 11 instead of 12 frames.