ste up

So I traded one of my 29 gallon tanks for a 55 gallon acrylic tank. My stand is coming in the mail soon. I have been told (or read somewhere) that an acrylic needs foam under it. What kind of foam? Styrofoam, neoprene mat, yoga mat? I have some 1/4 neoprene foam matting, about 5 feet of it...