Rubber Grommet --- Inner Diameter 5/16" --- Outer Diameter 5/8" --- Overall Thickness 1/4" --- For Panel Thickness 1/16" --- For Panel Hole Diameter 1/2" --- Used to Insulate and seal around holes cut in solid panels --- Also Used to dampen vibration and minimize abrasion. --- Durometer hardness - 55A. Can be used indoors or outdoors. Color is black. Flexible grommets made of SBR rubber Temperature range –56° to +200° F.