Check the listing for details. Aquarium Air Stone Disk Fish Tank Aerator Bubble Diffuser Hydroponics Stone. Condition: New. Listed at 2.12 USD. * Round Bubble Donut creates a healthy and decorative volcano of bubbles. The decorative volcano of bubbles distributes air evenly while assisting in maintaining an even water temperature and circulation. An aerated tank is healthy for fish, as air bubbles disperse gases through the water surface. Attaches to mini or standard airline tubing. Features: Creates a decorative array of bubbles. Includes: 1 (3") Round Bubble Donut; * Intended Pet(s): Fish; * Material(s): Sand & Plastic; * Product Dimensions: 3" (dia) Disk; * Assembly Instructions/Directions: Connect the air stone to the airline tubing and the airline tubing to the air pump. Place the air stone to the bottom of aquarium and cover it with gravel. * Non-continental customers, please contact us for additional freight to your area.