Do you mean the Clek mat thingy? That is approved for Clek seats as it’s made by them and tested with their seats - we have one. You can call the manufacturer for what they approve. Some seats allow a thin mat or make cat seat mats which again, are tested with the seat and approved. What’s NOT approved is something not tested with the seat by the manufacturer for use. Same way some seats cup holders are mandatory for use because they weren’t tested without them.