Hornady Canister Dehumidifier - The Hornady Canister Dehumidifier protects your valuables against rust and corrosion. When the moisture control crystals turn pink, recharge unit by placing it in the oven until the crystals turn blue (up to 4 hours). Protect Firearms And Other Valuables From Rust And Corrosion Desiccant Crystals Change Color When Canister Needs Recharging No Batteries Required Unlimited Recharges