Rubber Plugs - "Grommet Without a Hole" Fits 3/8" panel Hole Hard To Find Item Has 1/16" groove around outer circumference Can be used to seal hole in panel or create your own hole in center for custom application For Panel Hole Diameter 3/8" Outer Diameter 1/2" Overall Thickness 3/16" For Panel Thickness 1/16" Durometer hardness - 55A. Can be used indoors or outdoors. Color is black. Temperature range –56° to +200° F.