We stock 20 sizes, all of which are made from our trademarked Tufver Glass(tm). We separate these into two collections only for ease of shopping. The Prima Collection contains our 8 most popular and least expensive sizes, all available on one page. The Moda Collection contains 12 sizes, divided by distinctive shapes; XL sizes are larger, Round sizes are, of course, round and Tab sizes have the traditional tab built into the front for those who need a portion of their mat to continue into a desk opening.