12 - Silica Gel - Hydrosorbent 40 Gram Canisters Desiccant Dehumidifying Drying Unit Helps to keep moisture away from your valuables. Can adsorb 15 percent of its weight in water vapor in 2 hours. Reduces condensation and remains dry even during humid, damp conditions. Prevents rust, mildew, corrosion and spoilage before they begin. The 40 gram canister measures 4 x 2 x 1/2 and will cover an area of 3 CU. FT. of enclosed space.