... nonmetallic materials.2.Standard widths of 6, 12, 18, 24, 30, 36 inches3.Standard depths of 3, 4, 5, and ... 6 inches4.Standard lengths of 10, 12, 20 and ... nonmetallic materials.2.Standard widths of 6, 12, 18, 24, 30, 36 inches3.Standard depths of 3, 4, 5, and ... 6 inches4.Standard lengths of 10, 12, 20 and ...