A fitting for through hole mounting to a panel of a bathing installation includes in one exemplary embodiment a flange structure fabricated of a transparent or translucent material, the flange structure including a hollow body portion adapted to extend through a mount hole in the panel and having an outer peripheral portion, and a transverse flange portion having an outer size larger than the hole opening, so that a peripheral flange portion overlaps the panel surrounding the hole when the flange structure is installed in the mount hole. A light source attachment portion is attached to the body portion of the flange structure and configured so that with the flange structure mounted to the panel, light emitted from one or more light sources mounted in the light source attachment portion is transmitted through the body portion and into the transverse flange structure to illuminate at least a portion of the transverse flange portion.