Small Air Stone Cylinder: Size: 1.85" D x 1.9" L. The small cylinders are well-constructed for continual bubbling. Ideal for small fish tanks, DWC systems or small ponds. Medium Bubbles: With lots of micro holes which allow a good amount of dense and even bubbles to spout from the cylinder. A great way to increase oxygen solubility in your aquariums and enliven the aquatic lives. Steady Output: Jetting volume: 8 L/min; Recommended pump power: > 6 W; Standard ID airline tubing: 3/16". Efficient bubblers for constant air diffusion, keeping your fish or roots growing healthily. Stable in Water: Each aquarium air stone weighs 5.34 oz, making it quickly sink to the bottom. It always lies stably in the water and won’t move easily when bubbling. Easy to Use: Soak the stone completely in water for 1 hour before use. Clean it regularly with a brush as it gets clogged after weeks or months of usage. With lots of micro holes which allow a good amount of dense and even bubbles to spout from the cylinder. A great way to increase oxygen solubility in your aquariums and enliven the aquatic lives.