Ultra-thin and highly effective against airborne pollutants, Plastabs are available in three sizes, 1/2 in. square, 3/4 in. square, and 1 in. square. They are highly effective inhibitors for silverware, ferrous and non-ferrous metals, and glass. The proprietary V.C.I. formulation emits an odorless, non-toxic vapor which is diffused throughout the enclosed space until the air is saturated. The vapor then provides passivity to the surface of the artifact, protecting against tarnish and corrosion by reducing the electro-chemical activity on these surfaces. The lifespan is up to 12 months. The 1/2 in. Plastabs protect up to 150 cubic inches, 3/4 in. protect up to 300 cubic inches, and 1 in. Plastabs cover up to 500 cubic inches. Plastabs are available in packages of 20 of a given size.