We choose this best quality air stone that will create an abundant cascade of small to tiny bubbles rather than a limited number of larger bubbles. Can be easily driven by even Nano air pumps, suitable for aquarium, fish tank and circulation system. MODEL: ASD-040. Jetting Volume：2 L/min, suitable for approx. 11.8-23.6 inch fish tank. Recommended Air Pump Power: 2 W - 5 W. Fits for 3/16' / 4 mm inner diameter tube. Increases oxygen and lowers CO2 levels. Durable & washable. Sturdy and non-toxic material is Safe to your fish. Please soak the air stone in water for about 30 minutes before usage. Remember that any air stone will need to be replaced every few months as they get clogged with dust, bacteria, and algae. Comes with 4PCS air stones. Size: approx. 1.6 x 0.6'/40 x15mm (D x H).