Red Devil Cartridge Caps protect unused caulks and adhesives. An insertion rod plugs the cartridge opening, forming a complete seal. Don't throw away unused caulk, when you can save on time and waste. This unique sealing method prevents sealants and adhesives from drying out and reduces the mess of after flow. It is easy to store and not get lost. Before caulking, simply clip it to a caulk gun release bar for quick and easy access.