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.