I've had my chair mat for three days and I'm already pulling myself out of the craters I've made by sitting in one place while clicking away on my p/c.I realy thought $70 bucks was going to do it I'm realy disapointed.I will say it protects my flat(not plush)rug but at an inconvenience.I'm thinking plywood then the mat. I use a 4 wheel office chair and weigh 210 lbs which I'm sure add to the dips and divots.