These proprietary Volatile Corrosion Inhibitor (VCI) plugs fit in the chamber like a snap cap to protect the gun from moisture, rust, and corrosion. Special wicks emit a vapor barrier that bonds with oxygen and water molecules to make them incapable of starting the corrosion process, allowing them to penetrate the smallest cracks and crannies to stop rust in its tracks. Leaving no smelly odors or residue and lasting up to one year, these plugs are safe for all metals, including carbon steel, stainless steel, aluminum, brass, bronze, and copper, as well as wood and synthetics. Available in .22 caliber for pistols, universal pistol, 12 gauge, 20 gauge, and a 3 pack for .222-.223;.243;.308;7mm-08;.270;30-06.