A fitting for through hole mounting to a panel structure in a bathing installation includes a fitting body structure including a body portion configured to extend through a mount opening and a transverse flange portion having an outer size larger than the mount opening to overlaps the panel structure surrounding the mount opening. A nut engages a portion of the body. A ring structure is positioned between the nut and the panel structure, and has an inner opening with a dimension larger than a diameter of the nut and larger than a dimension of the mount opening, and fits between the nut and the panel structure. A seal is disposed within a cavity defined by the ring structure, the panel structure, the fitting body portion and the nut to provide a water-tight seal.
