kent1146:They both do about the same thing... regulate humidity to around 65% to 70% (depending on which kind you buy).The guys at my local B&M store (Holts, in downtown Philadelphia) swear by the idea that you keep the green sponge, and combine it with a beads / gel product. Use a 50/50 mix of distilled water and propylene glycol in the foam. Also, stick a jar or two of beads / gel in the humidor. The purpose of the green foam is to provide the humidity, while the purpose of the gel is to regulate humidity.