Simpooltec Skimmer Plug AG WIDEMOUTH 5 3/16" x 11 3/16" - Fits Hydro-Tools #8939 Skimmer Provides a simple solution to winterizing your pool without having to drain any water Simple installation requires no tools Chemical, temperature, and UV resistant Fits Hydrotools skimmer models 8939 widemouth AG 2014 and prior Inside dimensions: 11-3/8 inches W x 5-3/16 inches H