uxcell Black Gray 6mm Outlet OD Air Bubble Stone for Aquarium Ponds Product Name: Aquarium Airstone Outlet Hole Size: 6 x 3mm/ 0.24" x 0.12"(OD*ID) Total Size: 11.3 x 3.8 x 3.8cm/ 4.4" x 1.5" x 1.5" (L*W*T) Weight: 108g; Color: Gray & Black; Material: Mineral Stone & Plastic Package Contents: 1  Aquarium Airstone