Hydrosorbent SG40 40 gram Silica Gel Canister, Model: SG-40 Silica Gel 40 Grams. Protects 3 cubic feet of enclosed space. Desiccant of choice by government and industry. Needs No electricity, can be reactivated in 3 hours in 300 degree oven. Indicator window indicates when the unit needs to be reactivated.