Crack Monitor: The crack monitor consists of 2 plates with overlapping partial lengths. The bottom plate is calibrated in millimetres, the top plate is clear and marked with a crosshair cursor. Practical and convenient to use. Practical: The crack monitor can be used for monitoring cracks in walls and their evolution over the measuring time. Easy to Install: 2 plates can be easily fixed together without the need for glue or complicated installation steps. It is convenient and stable to use. Accurate: The crack monitor with highly clear acrylic plate allows easy to read and watch the data. The scale plate is designed with scale in both horizontal and vertical directions. The Indicator plate has crossed indicator lines design. Quality Acrylic: This crack monitor is crafted by quality acrylic, sturdy and enduring. And it is to water; scratch and sun. Easy to install and reusable., Weight: 0.23368999772 pounds, Manufacturer: Ehwisbe