A levels of the type including an elongate hollow frame and a magnet secured to the frame having a magnet-mounting structure which includes first and second magnet-holding members positioning the magnet with respect to a bottom-wall opening. The first magnet-holding member has a first side flange; and the second magnet-holding member has a second side flange. Each side flange is positioned to extend along one of opposite frame sidewalls at an inner surface of a frame bottom wall. A locking member pulls the magnet-holding members together such that the side flanges are locked inside the level frame along the opposite sidewalls, thereby mechanically securing the magnet to the level frame.