I have medium pile carpet and my casters sink into it and create divots/depressions and doesn't roll. I will return it and hope the one for heavy duty carpet works. The chair and I probably weigh 230 lbs.
Shifts position with movement of chair and as a result it tends to develop humps/bulges due to stresses on the plastic. Also the mat develops indentations or pockets where the chair weight presses downward under the casters.
Mat is perfect size however the material is too thin and soft. I weigh about 180 lbs. and my chair is a basic office chair. Makes huge dents under each caster wheel. Time will only tell how long this mat will last.