Features: This is a very nice tiny Co2 Glass Monitor. Made of quality glass. Specially for pressurized CO2 system plants for tank. Used to test and monitor the concentrate of the aquarium water plants fish for tank. No suction cups required. Simply hang it on the edge of your planted aquarium. Easy maintenance, since it is not under water, it won'for t grow algae on the glass. C02 indicator reagent not included! Specifications: Material: Glass Length: app. 6cm/2.36'' Color: Transparent Note: 1.Please allow 1-3cm error due to manual measurement. pls make sure you do not mind before you bid. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package includes: 1 x Glass Monitor (C02 indicator reagent not included)