I measured my carpet as directed and chose the low-pile based on that. This mat is too soft for my carpet and the wheels on my desk chair sink in creating divots that it's hard to wheel out of. I stopped using it after a week and it's now sitting on my cellar's cement floor.
So far so good - after just a week or two. Shipped flat so easy to start using without having to work to get it to be flat. The nubs on the underside are shorter and not sharp as compared to most mats - so no chance of scratching yourself badly. t does not have a lip - which I love. I got this one so I can slide side to side and still be on the mat - and to potentially have two chairs side by side on the one mat.
Got it wrapped in adhesive tape that would not come off. Had to buy goo gone and spend many hours getting in off. I paid pretty good money for the Mat but was disappointed that it was delivered with melted adhesive glue all over it.