This extra durable Alvin 12" x 18" self-healing and reversible cutting mat is 3mm thick, green on one side, black on the other, with grid lines on both sides. Grid has 45 and 60-degree angle guides and .5L inch marks. Constructed from a unique high quality composite vinyl material designed for both rotary blades and straight utility blades, this mat provides a long-lasting, non-glare surface that can be cut and slashed constantly without showing marks or cutting lines. With a medium tooth surface, this mat can also be used as a desk blotter or general-purpose work mat. Has hanging hole for convenient storage. Find the perfect center on any project with zero centering lines.