Zerust has proven to be the absolute best way to protect your weapons against rust and corrosion. Molded right into plastic, this patented polymer emits a harmless vapor, forming a protective layer around metal surfaces. All Zerust products will maintain their effectiveness from three to five years or more, so you can count on hassle free, long lasting protection with our Tuff Tainer utility boxes. Zerust Capsules are perfect for tackle boxes, firearm cases, truck boxes, ammo boxes, tool boxes etc...