Tetra Whisper Assembled Bio-bag Filter Cartridges, Large, 6-Count Large, 6-Count (2 pack of 3-Count); Conveniently Assembled and Ready-to-Use, Easy to Assemble, Easy to Replace; Keeps water crystal clear; Mesh Catches Debris And Fish Waste. Removes odors and discoloration; Fits whisper power filters 20i,40i, c,20,30,40, and 60.