The Aquatop BREZA Sand Airstones are uniquely shaped and boast an incredibly porous surface, which allows for consistent even air distribution. This even air flow creates a beautifully consistent column of bubbles.Aquatop BREZA Sand Airstones provide the oxygen your aquarium fish and plants need for a healthy life. Made from pressed sand, the BREZA airstones allow for uniquely even air distribution in the tank, with a notched shape to increase bubble-producing surface area for maximum aeration. Features:• Pressed sand composition allows for even air distribution• Unique shape & incredibly porous surface area• Provides oxygen for the health of aquarium fish & plants• For Fresh and Saltwater Aquariums