Set 2: 1 x 8-way O2 valve + 10 x Aqua Air Stone Product Name: Aqua Air Stone Size: 15 x 25 mm/ 0.5 x 0.9 (D*L) Connector size: 4.5 x 2 mm/ 0.1 x 0.07 (outer diameter * inner diameter) Total length: 36 mm / 1.4 Materials: Mineral, plastic/hard plastic Air can be distributed in the right proportion and supplied to your fish storage area with 8 manipulators. A lever valve can make it easier to use.