3 mm. Thick, extra durable, self-healing, reversible and non-glare surface. Non-stick surface is impervious to abrasions and liquid spills. Hanging hole for convenient storage. Printed grid pattern includes guide lines for 45 and 60 degree angles and 0.5 in. grid lines. Edges are fully numbered and graduated with 0.13 in. hash marks that extend beyond the zero base line. Internal horizontal and vertical graduated hash marks. Designed for both rotary knives and straight utility knives.