18" x 24" Olfa® Mats Markings extend to mat edge. Now you can line up your ruler more accurately and use every mat inch. Self-healing mat base consists of three layers: a soft layer, a hard layer, and another soft layer to prevent wear and tear on cutting blades. Use either side for cutting with your Olfa Rotary Cutter. One side of green mat has yellow 1/8" hash marks, 1" grid marks, plus more clearly labeled angle and bias lines. Store mats flat; sensitive to excessive heat.