Everbilt 1/2 in. x 5/16 in. Black Rubber Stopper

Rubber stoppers have a tapered shape to fit various sized openings and provide a secure, watertight seal. The solid, synthetic rubber construction can be cut to an exact length and is very elastic. Commonly used as a bottle stopper for glass containers, in electrical boxes and various household or shop applications. The tapered shape allows one size stopper to fit variously sized openings.