In addition to the different sizes of tanks that are available to the Tank System, the SKYsmoke collection also has refillable wadding cartridges. In the standard package there are 5 reusable empty wadding cartridges and just like the tanks, they are meant to be filled with the e-liquid. With one filled cartridge you can smoke the e-cigarette almost a whole day. You can refill the wadding cartridge maximum of 25. To fill the cartridge, the e-liquid must be purchased separately.