I have the large 36X30 and love it. Have a small 12x12 that I use at the side of my machine when I need to cut peices that have just been sewn and pressed. The worst thing that can be done to a mat is to accidently expose it to the heat from the iron (had my pressing station sitting on it, bad idea). It warped and could not be straightened out, so I cut it into smaller boards to use at classes etc. Also they make great templates, just cut with a straight edge ruler and a utility knife.