The horn fits perfectly on top of seven π-18 speakers, which are those using 18" woofers. On those cabinets, the sides are the same width.seven π-18 cornerhorn
But on the smaller cornerhorns with 15" woofers, the midhorn is a little wider.
seven π cornerhorn
I put the midhorn on my seven π speakers, and it really looks pretty good.
seven π cornerhorn, midrange horn close-up
I had originally hoped to make a smaller midhorn for the seven π speakers that wasn't as wide but two things made me change my mind. The first is that the midhorn really needed the size to get bottom end response. It's pushing it even with this larger size and they need boundary reinforcement. The second thing is that when I placed them on the seven π cabinet, they actually looked pretty good.