foam

Hello all. What is the name of the foam that you put underneath the aquarium to prevent seen and unseen imperfections in the stand surface, from causing torsion related tank damage? I picked up a cheap 29 gal from petco ($40...50% off sale) as I don't want to wait a year to afford a decent used...

OK - been thinking since I am building a 125 gallon mixed, well it's done but I might change some things, like rock work, LOL I have had my arches fall now twice, I used silicone which only lasted 10 months and then epoxy another time. Ugh! Neither worked. :swear: Sooo I am thinking...