Usage When measuring small size within 900mm, no drawing measuring rule is required. Use slide rule according to the position of the ranging point.The level (in the level of the level display) shows the measurement. The measurement reading is read on the slider.When measuring a size of about 1800 mm, the inner rod that is stretched out and stretched is used, and measured according to the level displayed by the level. The measurement reading is read on the slider holder. Smoothly pull the ruler during the measurement (in the level of the level display).The vertical ruler is directly at the measuring point, adjustable up and down, and is screwed to the vertical position to maintain the level (in the level of the level display). Specification: Material: Aluminum alloy Color: Blue-black Gross weight: 3.8kg Product size (with aluminum box): 102×20×10cm/ 40.15×7.87×3.9" Package size: 104×20×10cm/ 41×7.87×3.9" The high-precision measuring ruler is made of aluminum alloy material with high strength. The high-precision measuring ruler has a small volume and light weight, allowing one person to complete the measurement independently. The high-precision measuring ruler has high accuracy, and the measurement error is less than 1mm. Note: Please read the instructions before use to ensure that the measuring rule can be used correctly.This product is made of aluminum alloy. Please handle with care when using. It is strictly forbidden for heavy objects to touch.Do not touch fire, rubber water, asphalt waiting for corrosive substances. If you accidentally touch a liquid such as paint, immediately rinse it off with a small amount of water and wipe the measuring ruler clean.The magnetic probe of this product is inclined after use. Do not pull it out vertically to avoid injury.