Product Name : Aquarium Air Stone;Stone Size : 24 x 15 mm / 0.9 inch x 0.6 inch (L x D)Connector Size : 4 x 2.5mm / 0.15 inch x 0.09 inch (Outer Dia x Inner Dia);Total Length : 38mm / 1.4 inchMaterial : Mineral, Plastic;Color : grayWeight : 132g20 pcs gray mineral bubble air stone, help to refresh the dissolved oxygen in tank water and keep fish live in a better environment.Produce mini bubbles, increase the breeding density, effectively create water currents and improve water quality in tanks.Package Contents : 20 Pcs x Aquarium Air StoneOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.