I would call Aqueon to confirm which if any panels are tempered. Their technical specs says the "no" for tempered bottom on a 40B. I have a 75 which is tempered bottom only.
Be careful buying Tetra tanks. I've experienced how poorly they are made, and there's no QC from the mfg. You have to QC the tank when buying. I had to return a 40B due to a bowed bottom. All the replacements they had came with misaligned corners and sloppy silicone. It was for a sump, so it didn't matter.