Because our Gauge can monitor cracks in wall and how they measured, it is very practical and for you Monitor features a highly clear acrylic base paired with easy-to-follow measurement lines, making analysis accurate and effortless You can use our Corner Monitor to monitor the horizontal or vertical movement of cracks on a plane It is a carefully designed instrument Our Measurement Tool features a millimeter-calibrated base and a clear top plate, incorporating a perpendicular reference line for alignment Gauge Monitor is constructed from premium-grade acrylic, providing excellent longevity, structural integrity, smoothness, and resistance to wear, Manufacturer: OSNIYAW