No eurobtace on back panel? Red Sea

[yamahadave]

I had a nano about 10 years ago.
Just acquired a Red Sea Max S500.
Couldn't help but notice that its eurobraced on 3 sides.
Why is the rear panel not braced?
Is it not under the same pressure as the front?
Looks like 1/2" just like the rest. Any ideas?

 

[yamahadave]

Disregard.
I figured it out