Specification:Measuring Range: 100cm / 39.37"Minimum Scale: 0.1mm / 0.004"System: Metric & EnglishMaterial: PET PlasticThickness: 0.1mm / 0.004"Features: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. In addition, it has an R angle scale, which is convenient for measuring the radius of rounded corners. There are width lines of different sizes in the middle, which can measure whether the thickness of the line meets the standard.