Below is a list of Rubber Grommet manufacturers from Rancho Cucamonga, California. Rubber grommets are rubber rings placed around an opening in a surface. Grommets are usually intended to protect either the opening from tearing or breaking, or they are intended to protect whatever objects that pass through the opening. Rubber grommets typically serve the latter function, as they often protect wires or cords that pass though openings in metal surfaces that would otherwise be too jagged or sharp.