Purchased this because the pillowtop on our new mattress wasn't thick enough to give you that "ahh" feeling when you sank into bed. This product delivered. We've slept on it every night for a month and we love it. It fits like a glove: complete coverage from top to bottom and side to side. Our mattress is 12' deep with a pillowtop on top of that, but I had no problem getting the deep pocket fitted sheet to fit nicely over the mattress, pillowtop and this fiberbed. The sheet holds it in place just fine. It does compress a little bit each night (not enough to interrupt our sleep,) but seems to fluff back up during the day. I shake it and rotate it when I change the sheets, and after a month it's still as fluffy as the day it was delivered. It does NOT retain body heat and the baffles are really substantial -- nothing has shifted or flattened. We like the feeling of sleeping on a cloud and this fiberbed saved us from replacing our too-hard mattress!