The Airstone Cyl Carded 2 (10136) is a cylindrical, carded airstone used in hydroponics systems. It is designed to diffuse air into water, creating a fine stream of bubbles. This process helps increase oxygen levels in the water, which is vital for fish and plant health. The cylindrical shape of this airstone allows for efficient and even distribution of air bubbles throughout the water, promoting a well-oxygenated environment. It is a commonly used accessory for aquariums and hydroponic setups to improve water quality and maintain optimal conditions for aquatic life or plant growth.