Abstract: A mason ruler consisting of a central profile (27) made of solid wood and other materials, which has its own section in the two long parallel sides (28) and two smaller parallel sides (29). The extremities of the longer sides (28) of the section of profile (27) have recesses (30), which extend along the length of this central profile (27). O each lower side (29) and their two respective adjacent recesses (30), is mounted a letter-shaped profile U (25) preferably composed of aluminum. This ruler has integrated into its body at least one unit tool level (26), which may be a bubble level or any other principle of operation.