Abstract: A spirit level vial construction provides various refinements in the structure and method of manufacture of vials used for the containment of fluid and adapted to be installed in spirit levels. The construction is particularly adapted to use with spherical vials, i. e., level vials having a concave spherical form within the sight glass portion containing the bubble, and adapted to provide level information relative to a planar surface. However, the present construction may also be used for tubular type level vials. Vials using the present construction are formed of plastic materials (particularly acrylics) for economy, and are preferably molded by an injection molding method in order to reduce substantially any warping or deformation during the molding process. Various clear or dyed fluids which are compatible with the plastics may be used, particularly mineral spirits.