Use mats with a smooth back . Spiked mats will damage hard floor finishes. The "Paperclip Test" for Carpet
Straighten a paperclip and push it through the carpet and padding until it hits the subfloor. buy chair mat
Use mats with grippers or cleats on the bottom to anchor the mat in place. Use mats with a smooth back
Mark the point flush with the carpet surface and measure that length. Requires a standard thin mat. Medium Pile (Up to "): Needs a thicker mat with slightly longer spikes. High Pile (Over buy chair mat