EUC Cirkul water bottle. Better for the environment. One cartridge replaces the equivalent of 6 single use plastic water bottles. Better for you. Flavor cartridges have 0 calories, no artificial colors, no artificial flavors and zero sugar. This listing is for the water bottle only. You will need to buy Cirkcul flavor cartridges (see third photo). First photo shows water bottle with a flavor cartridge installed. Second photo shows water bottle without a flavor cartridge installed. Flavor cartridges are easy to install; they just twist in/out.