Pack of 2 IPW Industries Inc. 20" x 2.5" premium coconut shell granular activated carbon filters. Additional Details ------------------------------ Bullet point: Pack of 2 filters|20" x 2.5" Granular Activated Carbon Filters|When you initially turn on a tap after installing a new cartridge you can notice black or gray suspended particles carbon fines.|While they are totally safe it can be unpleasant for you to have them in your water.|Another reason to flush a GAC whole house water filter is turbidity that is just an air carbon tends to release when contacting with water for the first time.|To get rid from both issues just pass several gallons of water before putting a new cartridge into service.|Filter life 3-4 months depending on water quality.|Compatible with iSpring FG25X4 Premier Water Systems 4pcsGAc Premier 15pcswf Hydronix UDF-20 Geekpure GAC-20 Crystal Quest CQERC04024 Geekpure 122-20 Pentek 150560 3G-STANDARD-34-PR20 150166 153013 158129 158204 150009 150564 Hydronix HX-HF5-20BLBK34PR HX-HF5-20BLBK34