At the same time comfortable soft writing surface and insensitive base for cutting work: Printed on the green top side with 10 and 50 mm graduations and underlaid grid - plain black and unprinted on the reverse side. 5-layer "sandwich soft" construction with hard core. Layer 1 = 0.1 mm soft material Layer 2 = 0.8 mm soft material Layer 3 = 0.8 mm hard material Layer 4 = 0.8 mm soft material Layer 5 = 0.1 mm soft material = 2.6 mm ~ Tolerance total 0.2 mm