Features 1、Best helper: This is an important tool for monitoring the CO2 content in an aquarium. 2、Display color: If the CO2 content in the aquarium is insufficient, it will display blue, when it is normal, it will display green, and yellow means CO2 excess. 3、Channel thick design: The wide channel design facilitates the addition of the detection liquid, while making the diffusion of air molecules easier, and shortens the reaction time of the detection liquid. 4、Strong suction cup: The extra-strong suction cup holds the endurance test firmly on the window. 5、Glass material: Clear, perfectly shaped glass, as is also used in laboratory equipment, makes the long-term test a real eye-catcher. Specifications Material: glass Size: about 4.2 * 2.5cm / 1.65 * 0.98 in Suitable for: Long-term carbon dioxide monitoring Instructions for use: 1. Place the inspector up. 2. Put 5 drops of test solution into the inspector. 3. Refill the aquarium water into the water line. Note: Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering. Package List 1x carbon dioxide detector 1x test solution 15ml