This simple design is easy to clean, provides diffused oxygen, creates fine bubbles without using strong output pump. Instructions: Soak the air stone in warm water for 30 minutes before first-time use to open its pores for maximum bubble output. If the airflow decreases, soaking the stone in a mild bleach solution (then rinsing and drying completely) will clear the pores. Rinse very thoroughly before returning to aquarium. Use air controller to adjust the output. The smaller the output the finer the bubbles. Includes Refiner airstone, 2 suction cups, check valve, and air control valve. Airline tube not included.