Put this Crystal Gel Tube into your humidor to provide long lasting humidification or as a boost to your present humidifier.  They are designed to maintain a 70% RH (Note:  Several factors can affect your actual humidity within your particular humidor, tupperdor etc).  The Drymistat's small size (the size of an average churchill sized cigar) permits easy placement within your humidor.  These tubes will humidify up to 25 cigars.  Purchase more units for larger humidors.  Refill (as needed) with distilled water and fill up to the line and your off and running. The manufacturer states that you can use plain tap water, but we recommend distilled water if you have it on hand.  These little humidfiers work very well and it's easy to see when you need to refill it with distilled water.  No extra messy chemicals to buy. Note: Drymistat logo and cap color may differ from the image shown.