Uxcell 5-Piece Cylinder Aquarium Mini Air Bubble Stone Set, 15mm Diameter, Black Aquarium Airstone; Color : Black Material : Mineral Stone, Plastic; Cylinder Size : 22 x 15mm/0.86" x 0.59" (L*D) Tube Size : 4.3 x 2.5mm/0.17" x 0.1"(H*D) Weight : 32g Package Contents : 5 &times; Aquarium Airstone