Saim Black Media Bio Balls Filter Strainer for Fish Tank Aquarium Pond

Amazon.com Price: $8.99 (as of 25/03/2022 18:26 PST- Details)

0.63″/16mm Ball in diameter
BIO-Balls do not require replacement unless damaged or destroyed.
Bio-sponge inside provide more surface area for growth of beneficial Bio-Spira bacteria.