Features:

1.The bio-sponge inside provide more surface area for growth of beneficial Bio-Spira bacteria

2.BIO-Balls do not require replacement unless damaged or destroyed

3.In the event of excessive buildup, you may gently rinse with water from an established aquarium, if desired

Dimensions:Diameter of bio ball: 32 mm

We can also offer 22mm.33mm.36mm.42mm.45mm.48mm.and 55mm