This 5″ around Bubble donut air-stone from Marine Metal Products is specially designed to aerate water and keep bait alive. The air-stone can be used in both fresh and saltwater of minnow buckets, live wells, coolers, and more. Tough and durable construction is weighted so it stays properly positioned on the bottom of your tank or bucket. Will work with 12V, 110V, and D-battery powered pumps.