24"X36" Omingrid Mats have several unique features that quilters appreciate. The mat reverses from a medium green with grid lines to a light grey without grid lines. The grey side is easier on eyes and useful when working with different fabric values (choose whatever offers the most contrast for accurate cutting.) Ominigrid markings are distinct and readable and they line up with Ominigrid rulers. The outer dimensions is 1" larger which gives a larger cutting area. Also, the mat surface is smooth which keeps the rotary blade sharper longer.