Planet Waves Humidipak - Automatic Humidity Control Systemstar rating 2Erik in MasisonApril 13, 2011Pros: easy to use, not messy, separate packs for hanging on strings and for the neck area, little monitoring necessary (don't have to fill or check every few days like other systems) Cons: refill packs last from one to three months in humid conditions to only a week or two in dry conditions (winter in Wisconsin) and therefore can be quite expensive to keep buying refill packs. Product is well designed but expensive - plus, you're throwing away a lot of stuff (landfill)