Feature: 1. Sturdy and durable material, can be repeatedly cleaned, long time using. 2. Special stainless steel connector, more durable to use. 3. High temperature firing, good air permeability, help fish to survive and breed better. 4. Exquisite stone shape design, frosted surface, delicate and smooth. 5. The air volume is large and the air output is even, to increase the oxygen content in the water. Specification: Condition: 100% Brand New Item Type: Bubble Stone Material: Sand Stone + Stainless Steel Color: As Pictures Shown Optional Diameter: Approx. 6cm/2.36inch, 8cm/3.15inch, 10cm/3.94inch, 12cm/4.72inch, 15cm/5.91inch, 20cm/7.87inch 6cm Diameter connect 4mm air tube 8cm Diameter connect 4mm air tube 10cm Diameter connect 4mm/8mm air tube 12cm Diameter connect 4mm/8mm air tube 15cm Diameter connect 4mm/8mm air tube 20cm Diameter connect 8mm air tube Package List: 1 x Bubble Stone Note: Note： Soak the product in water for 15 minutes before using. Product Function：Connect to the air pump, and put into the water to help the air pump to put oxygen into the water(need to connect the air pump to have air! Products without any accessories, need to buy).