Measure the cross-sectional area of the specimen at several points along its length. Measure the width to an accuracy of 0.25 mm (0.010 in.) or better. Measure the thickness to an accuracy of 0.0025 mm (0.0001 in.) or better for specimens less than 0.25 mm (0.010 in.) in thickness and to an accuracy of 1 % or better for specimens greater than 0.25 mm (0.010 in.) but less than 1.0 mm (0.040 in.) in thickness