uxcell 5-Piece Round Base Bubble Fish Tank Release Maker Air Stone, Black/Gray Aquarium Air stone; Color : Gray, Black Material : Mineral Stone, Plastic; Outlet Hole Size : 4 x 2.5mm/0.16" x 0.1"(OD*Inside Dia.) Stone Part Size : 58 x 14mm/2.3" x 0.55&ldquo; (L*D);Total Size : 88 x 18mm/3.5" x 0.7" (L*D) Weight : 99g Package Contents : 5 &times; Aquarium Air stone