The mat was in the trunk of my car for about an hour while I continued to shop. When I got home it appeared to have melted and developed major creases and bumps. I had to lay it in the sun and stack weights on it to get the lumps and bumps to go down. It will never have a crisp and flat surface. I should have purchased the expensive heavy weight one.
When I sit for any length of time the wheels of my chair create deep impressions in the mat and my chair gets stuck. I weigh 170. I did not have this problem with a previous mat. When I am not using the mat the impressions do fade but never completely.