["brand new and high quality Features: Made of high quality material, which will be durable and reliable. With non-return function to prevent the backflow when the pressure changes, and this can ensure the water plant table and CO2 bottle from damage. It can count the volume of carbon dioxide and supply the plants with enough carbon dioxide. East to install and use, a good choice to make your fish for tank different. Double for head and single for head are available, you can choose according to your needs. Bubble Counter only,other accessories demo in the picture is not included. Specification: Material: Aluminum Alloy Size: app.7.9x2.1cm/3.11x0.83in Color: Silver Optional Style: Double for Head, Single for Head Quantity: 1 Pc Install Method: Single for Head Bubble Counter: 1. Take out the seal ring and install on the trachea interface of the valves, then tighten the bubble counter. 2. Add 4/5 water in the bubble counter and then tighten the top cover. Plug the CO2 pipe and then tighten the trachea fastening nut. Double for Head Bubble Counter: Add 4/5 water in the bubble counter and then tighten the top cover. Plug the CO2 pipe and then tighten the trachea fastening nut. Note: No retail package. Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package Contents: 1 x Bubble Counter"]