Abstract: A spirit level including a frame having parallel working surfaces and a web interconnecting the working surfaces. One or more vial openings of regular octagonal configuration are formed in the web. A vial case member having an octagonal wall is selectively positionable in the opening in the web with the vial extending either parallel to or perpendicular to or at an angle of forty-five degrees to the working surfaces. A second vial case member is disposed at the side of the web opposite the first mentioned case member and bonded to the octagonal wall on the case member to hold the case members in assembled relation on the web. A pair of case covers of like configuration are mounted at opposite sides of the web with hook portions on the cover members extending through openings in the web.