I bought one and loved it so much that I ordered a large one to fit over my bigboard. I use a steam iron with it, and let it sit on a seam for about 20 seconds. I get absolutely flat seams that stay flat. I can’t tolerate smelly things, but my mat doesn’t smell bad. It’s one of the best tools I’ve ever bought right up there with my Martelli cutting table and my Bernina sewing machine.