Medium Bubbles: The air stone balls produce a good amount of dense bubbles. A great way to increase oxygen solubility in your aquarium and enliven the aquatic lives. Model: ASR-030; Jetting volume: 1 L/min; Recommended air pump power: > 2 W; Standard ID airline tubing: 3/16". Well-built and efficient for long-time service. Reliable Material: Made of mineral material and sintered at a high temperature. Great for aeration in fish tanks, aquariums or koi ponds. Keep fish or roots growing healthily. Easy to Sink: Each ball measures 1.2" in diameter and weighs 1 oz. Well weighted to sink to the bottom and lie stably in your tank without floating up. Easy to Use: Soak the stone completely in water for 1 hour before use. Clean it regularly with a brush as it gets clogged after weeks or months of usage. The 1.2 inch air stone balls feature durability, steady bubbles and high dissolved oxygen rate. Optimal for aerating your water reservoirs and livening up your aquatics. A necessity to have in the house of aquatic lovers.