Description: The double-connected bottle Caps is made of high-quality PC plastic, which is not easy to rust, is made accurately, and is durable. Unique acid particles blocking filter to prevent clogging and corrosion tuning valve and prolong life. Tuning valve Removable cleaning.Transparent circulation piping, fluid flow can be observed at any time. Turning Clockwise is to increase the safety pressure level,the valve will let the CO2 gas release out of the bottle at higher pressure level automatically.Turning Anti-clockwise is to decrease the safety pressure level. This CO2 bottle Caps is suitable for most DIY reactors. It adds the amount of CO2 available to your fish and aquatic plants.Pure and long lasting Co2, promoting plants growing. Specification: Material: PC Plastic Size Chart: Size: 17.2x4.5x12.8cm/6.77x1.77x5.03inch Package Includes: 1 Piece CO2 Reactor Body 1 Piece Pressure Gauge (including safety valve) 1 Piece Fine Adjustment Valve 1 Piece Acid Suction Tube (including water absorbing ball) 1 Piece Acid Pipe (including tee) 1 Piece Magnet 1 Piece 1.6m Trachea 2 Pieces Spare Rubber Ring 1 Piece Manual (Chinese and English) Note: 1. Please allow slightly error due to manual measurement. 2. Due to the difference between different monitors, the picture may not reflect the actual color of the item. 3. Wish you a wonderful on-line shopping!