The folding ruler is made of PET clear plastic, which is worn resistance and unbreakable. It is durable and sturdy, has excellent light transmission, and minimal error caused by temperature for long lasting use.The office ruler is soft and has no sharp edges, so don't have to worry about hurting your hands. The ruler has a metric scale on one side and an English scale on the other for convenient measurement. The small ruler is perfect for factories, research institutes, measuring rooms and workshops use. It can be used to measure the area of a wide variety of products, accurately detect and calibrate various measuring instruments, measure the reduction rate of photo printing films and detect the size of optical projection maps, etc.