Rubber Grommet --- Inner Diameter 1/4" --- Outer Diameter 5/8" --- Overall Thickness 3/8" --- For Panel Thickness 1/4" --- For Panel Hole Diameter 7/16" --- Used to Insulate and seal around holes cut in solid panels --- Also Used to dampen vibration and minimize abrasion. --- Durometer hardness - 50A. Can be used indoors or outdoors. Color is black. Flexible grommets made of Buna-N rubber Temperature range 0° to +250° F.