RLX 12-210 Mushroom Plug Kit Mushroom style inserts are designed to “fill the injury” in passenger or truck, radial or bias-ply tires. Orange plugs are coated with a special vulcanising gum to ensure a fully vulcanised repair either chemically or in a heat curing system. Use the black, trigger type insert gun for easy installation. Kit comes complete with gum 3 packs of orange inserts, 2 sizes of nozzle and vulcanising glue.