Compatible with Marineland Magnum Polishing Internal Filter.
This product was easy to find and I ordered two three packs and it was still cheaper then one pack at other pet stores.
i use these in my pond, it is about 135 gallon outdoor tank ,( really a cattle water container) remove's algae and dirt, makes my pond CLEAR love it, hard to find something that keeps outdoor pond clear, but this is it
FOR THE BUCKS ITS A GOOD DEAL FAST AND AAA+++. THESE FILTER ARE JUST RIGHT, THEY DO THERE JOB WELL.
The sleeves that you shipped are not the right ones. They will not fit the Magnum 350
Works great, fits my filter just perfect, keeps my tank clean.