4 1/8" Disc Air Diffuser. Extremely durable and washable (reusable) air diffusing media. Manufactured with brown Adamantine Spar (corundum/alumina) under ultra high tempeature and pressure. Applicable in Acidic or Alkaline waters (low or high pH) Ozone resistant. Suitable for aquarium, koi pond, fish hatchery and aquaculture applications. * Outlet: Fits 3/16" & 3/8" ID Tubing