When this mat arrived it was fairly warped probably from having been rolled up at the warehouse. Luckily the day after it arrived the sun was shining brightly. Placing the mat on the deck in the sun helped flatten it also putting some heavy books on the edges helped. If you're trying to decide between two mat weights definitely go for the thicker one. This medium pile mat seems to be barely sturdy enough even though the rug + pad are quite thin.