Parallel level ruler is mainly used for checking unevenness and straightness in machine tool inspection. Two working surfaces are used in conjunction with block gauges, micrometers, level gauges, and other instruments to check different heights. The parallelism and non connection of two guide rails can also be checked with a right angle ruler. It is a measuring tool for checking the perpendicularity of two components that cannot be checked with a right angle ruler alone. Parallel level ruler is also suitable for equipment installation and inspection.