Let's find out :) and why!
The mats that I have are from Mountain Mist available at Quilt Shops http://mountainmistcrafts.com/pressing-mat/
or the large one here https://amzn.to/3sWH1sZ and the small one https://amzn.to/3op74Fx
The quilt in the background is in my book https://sewveryeasy.podia.com/hand-signed-copy-of-quilt-favorites-book and here is the video https://youtu.be/z_78C5bpdw0