40 Gram Silica Gel Desiccant (4 pack), top grade silica gel is contained within a compact aluminum canister. Provides lifetime protection and has a built-in indicator that turns from blue to pink to signal the need for reactivation. Easy to reactivate in any oven. Place the unit in a vented 300 degree F oven for at least 3 hours (or until the silica gel turns blue again). The more tightly you can make the storage area being protected, the better your silica gel will work. Silica gel beads are inert and non-toxic. The will Not emit harmful vapors, stain or cause any chemical reaction. Safe to use with foods, medicines, sensitive materials. Dehumidify any space to protect your coins, jewelry, electronics, films, RV's, safes, and so much more. Size: 4 x 2 x 1/2" , Protection: 3 cubic feet of enclosed space. Description: Prevents Rust, Mildew, Corrosion and Spoilage Crystals drink up moisture from the air Protect your valuables Reactivate Indefinitely Qty: 4 pack Ships FREE! A great gift idea for any Collector, Hobbyist, RV space and so many more. Ships FREE applies to the United States Only!