Very practical: Because our Crack Monitor is designed with super clear acrylic sheet and easy to read measuring grid, it is clear and accurate. Horizontal or Vertical Motion Monitor: As a precision instrument, our angle crack monitor can be used to monitor horizontal or vertical movement of cracks on a plane. Durable Material: Using high quality acrylic material, our crack gauge monitor has the characteristics of being durable, sturdy, smooth, tough wear-resistant and not easy to break. Consists of two boards: The crack measuring tool uses smart design. It consists of two planks which overlap for part of their length. The bottom plate is calibrated in millimeters and the top plate is transparent. Very practical: you can use our crack monitoring gauge to monitor the cracks in the walls and the progress process over measured time. It is very convenient for you. Note: The data is manual measurement, please allow 1-7cm error, due to differences between light and screen, there will be a certain color difference, the specific received in kind prevail.