Works with KleenTec product AF250 antifreeze recycling machine. Typically, you'll need to replace these cartridge type filters every 200 gallons or so. More frequently if your antifreeze is dirty and full of oil and rust. Less frequently if the glycol is fairly clean. Filters down to the finest micron level of any antifreeze recycler out there. That's just one of the reasons why the AF250 is the best coolant recycling unit on the market. These filters are sold in a case of 8. Sorry, they're not available in singles.