[Premium Acrylic Material] This crack monitoring record is made of high-quality acrylic material, which is sturdy and can be used repeatedly. It is waterproof, sunproof, wear-resistant, and scratch-resistant. It is easy to install and intuitive to read. [Advanced Technology] Our crack monitor gauge adopts advanced technology, perfect for tracking horizontal and vertical crack movement on flat surfaces. It enables reliable detection and monitoring of changes in crack width or length over time. [Purpose] This crack monitor gauge is designed to monitor cracks in walls and how they change over time. The instrument consists of a scale plate with scales in both horizontal and vertical directions, and an indicator plate with one or two crossed indicator lines. [Widely Used] Our crack measurement and recording instrument is widely used for observing the opening and closing of cracks and misalignment on various buildings. It can also monitor the relative displacement between two points in the horizontal and vertical directions. Parts List: 3 Pairs of Crack Monitoring Record 12 x Screws 3 x Monitors Our crack monitoring record is designed to monitor cracks in walls and how they change over time. It is made of acrylic material, which is waterproof and sunproof. It is reliable for monitoring and easy to read. Features: Waterproof Device: This crack monitoring record is waterproof and easy to install. It can be used for monitoring changes in crack width or length over time. Reliable to Use: This crack monitor gauge can be used for observing the opening and closing of cracks and misalignment on various buildings. It is reliable to operate. Specifications: Product Name: Crack Monitoring Record Measuring Range: -30 to +30 mm Resolution: 1 mm Measurement Accuracy: 1 mm Ruler Size: 100 x 30 mm Purpose: Can be used to monitor wall deformation and cracks Material: Acrylic Color: As Shown Package Contents: 1 set x Crack Monitoring Record Notes: There may be slight differences between the picture and the actual color of the item. We strive to represent the true color accurately. Please allow slight dimensional differences due to manual measurement. The package includes only the items listed above; other products are not included. Light reflection and different displays may cause the color of the item in the picture to appear slightly different from the real thing. The measurement allowed error is +/- 1-3 cm.