I have used several kinds but my by far favorite is Martelli. It is heavy duty, heat nor cold does not bother it (you can even press on it, which I don't do), it is both sided (purple on one side and yellow on the other), marked well, self healing, etc., etc. They are a little pricey but well worth it. Also love their rotary cutters. You can check the out on line at Martelli.com , they are out of Florida.