This short water cartridge for your Cigar Oasis Excel unit clips on the control unit and contains a foam element with the distilled water and antifungal agent. The water used will depend on many factors including the size of the humidor, how good the seal iis and how dry the cigars are when you place them inside your humidor. As a rule of thumb, a 75-125 cigar humidor will require replacing the water cartridge every 5-7 months. This cartridge does not include the battery pack. A full size cartridge and a short cartridge with battery pack are also available for the Cigar Oasis Excel unit. Not for use with Cigar Oasis Plus or Cigar Oasis Ultra. Size: 6"L x 2"W x 1"H