PROFESSIONAL SURVEYING: Bubble level is a common measuring tool mainly used to measure the levelness and verticality of objects; Check whether the tested object is parallel to the horizontal plane and whether it is tilted left and right. EASY TO USESimply place the level gauge at the location where it needs to be measured. When the bubble level is placed on a horizontal surface, the bubble will stay in the middle of the tube. At this point, it is possible to determine whether the object is horizontal. EASY TO ADJUSTMade of acrylic and ABS materials, the square bubble level gauge is as clear as crystal, and the measurement direction is easy to identify. When a bubble deviates from its central position, it is necessary to adjust the position of the object to bring the bubble back to its central position. APPLICABLE SCOPEHorizontal bubble square level precision bubble measurement kit, used for leveling photo frames, art photo frames and murals, hanging paintings, set-top boxes, levels, pan heads, precision instruments and other fields. PACKAGING LISTThere are 5pcs bubble level gauges, which are small and easy to carry, store, and transport. High precision, easy to use, fast and accurate. There are two black lines inside, with the smallest parallax error, widely used for professional measurement and daily use. Specification: Size:15 * 15 * 40mm / 0.6 * 0.6 * 1.6in. Package list:5 x String Line Spirit Level.