This is junk. The carbon is barely visible and it looks like most of it is on the outside of the filter. It was two 3-packs and they were all the same, so it wasn't just any random filter, they were all like that. See the photo of one of the filters I made. Unfortunately it has been too long since I bought them to return them.
Aquael Fan Filter Mikro Plus
35 Review
KEDSUM 330GPH Ultra Quiet Submersible Pump With High Lift And Grounded Power Cord - Ideal For Fish Tanks, Ponds, Aquariums, Statuary, Hydroponics - Includes 3 Nozzles And 1500L/H Water Flow
39 Review
Sink filter Prio New Water Start Osmos OU380 white
79 Review
KEDSUM Battery Aquarium Air Pump: Ultra-Quiet Rechargeable Fish Aerator with Dual Outlets - Ideal for Fish Tanks, Outdoor Fishing, Fish Transportation, and Power Outages
35 Review
Steam cleaner Deerma Deerma DEM-ZQ610 EU, white/red
68 Review
π U-BCOO Aquarium Gravel Cleaner Fish Tank: Manual Siphon for Efficient Filter Gravel Cleaning and Water Change in Tanks
22 Review
Jasonwell Magnetic Aquarium Fish Tank Glass Algae Cleaner - Floating Brush (L Size)
37 Review
Efficient 2-In-1 Magnetic Fish Tank Cleaner With Non-Slip Design And Scratch-Free Blades
37 Review