Features: Accurately monitor building wall crack with the crack monitorings record. Suitable for monitorings wall deformation/crack. Perfect for architects, constructions professional, and those who need to ensure structural safety. Sasy to installs, this crack gauges is crafted from acrylic material. The scale board and indicator board make measurements straightforward. Ensure safety of building structure by monitorings crack situations. Suitable for professional who need to monitor wall crack, this crack gauges provide accurate measurements. Suitable for various buildings, including residential and commercial structure. Widely used for observing crack opening and displacement on buildings, the crack monitorings record is suitable for monitorings relative displacement. Suitable for residential buildings and public facility. With its highs precisions measurement and easy installation, the Buildings Wall Crack Monitor Crack Gauges is essential tool for the constructions industry. It ensures safety of building structure by effectively monitorings and measuring wall crack. Maintain the integrity of your constructions with this reliable crack gauges. Specifications: Material:Acrylic Quantity:1,2,4 Measurement range: -30~+30mm Resolution: 1mm Measurement accuracy: 1mm Size:Approx.10cm/3.94'x3cm/1.18' Package Includes: 1x or 2Pcs or 4Pcs Crack Gauges note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual color.