Abstract: A bubble level with a hollow metal section has a circular window, in which a cylindrical level tube for a vertical level can be inserted with a positive interlock in the axial direction and can be fastened with a material interlock. A level support is inserted into the hollow section in the axial direction. The support has a cylindrical seat aligned with the window, to receive a level holder that bears a level. An interlock device is disposed between the level support and the level holder. By means of this interlock device, the level holder is mounted axially fixed, but rotatable until it is fastened by the material interlock.