Calming Pets Simple Carbon Filter Pads 
Change Ammonia Reducer, compatible with Quiet Flow Specialty.  
Aquarium filter foam pad reducer for Aqueon 10, 20, 30, 50, and 75 
Hang on back cartridge filter replacement  
Bulk Pads cuts can vary in size slightly– but will alway work great in your filter media. 
Same product, with no fancy packaging this will keep cost down.