From the Manufacturer Self-healing Rotary Mats Are Double-sided, Triple Layer With A Dark Green Base Color And Yellow Grid Lines On One Side For Detailed Cutting And Solid Green On The Reverse For General Cutting SELF HEALING ROTARY MAT - Our rotary mat is self-healing, it reseals surface cuts for a continually smooth cutting surface. Using a self-healing cutting mat extends the life of your blade and protects the surfaces of your work area. DOUBLE SIDED - Our double-sided rotary mat has one side with grid lines and one side without grid lines. Grid lines help with easy measuring and accurate cutting of straight lines and precise angles. The solid color side is used for general cutting. 18 INCH BY 24 INCH MAT - This rotary cutting mat is 18"x24" and 1.5mm thick. It's perfect for small and medium-size projects. Great for cutting multiple layers of fabric into bias strips, squares, triangles, and squaring up blocks. PROTECT YOUR ROTARY MAT - Our professional quality cutting mat is designed for use with rotary cutters only. Not for use with fixed blade utility knives. To prevent warping, store it flat and out of direct sunlight. THE OLFA STANDARD - As the inventor of the Rotary Cutter in 1979, OLFA has maintained a standard of cutting excellence for our quality and durability. Pairing OLFA brand rotary cutter, blades and cutting mats together will provide optimal results.