I thought this product would work on a relatively thin carpet with underlay but with even a small amount of weight the chair will constantly settle where the chair rollers meet the mat. Not workable for anything with an underlay.
Mat does what it's supposed to do...protects the floor. I only wish I bought one sooner because my daughter has scratched up my hardwood floors in her room while sitting at her desk. The only issue I do have with the mat is that is does slide pretty easily so I fix it probably everyday.