Tetra Whisper Bio Bag 20-60 Filter Cartridges remove odors and impurities from the water for a pure aquatic environment. The easy to assemble Bio-Bags make aquarium maintenance easy, and feature highly absorbent carbon that removes odors and discoloration. Meanwhile, dense mesh catches debris to provide clean, clear water for your aquatic pet.

Features:

Highly-absorbent carbon removes odors and discoloration for clean, clear aquarium water

Dense, dual-sided mesh catches debris and fish waste to help maintain purity

Convenient, easy to assemble Bio-Bags are easy to use
Includes: 3 or 12 count
Intended For: Aquariums
Size: Fits 20i, 40i, C, 20, 30, 40 and 60 power filters 

Instructions: 
For best results change Bio-Bag monthly