The Hornady 95908 Silica Bag absorbs humidity from enclosed areas and helps prevent rust, mold and mildew. Its moisture control crystals change color to indicate when unit needs recharging. This silica bag works anywhere without any electricity. Use for gun safes, gun cabinets, ammo cans and vault rooms. Silica bag can be recharged in a warm oven at 220 degrees for up to 4 hours.