A year ago, I purchased a home with a 25 cf french door Whirlpool refrigerator. The water filter requires a Number 4 filter replacement. I opted for Waterdrop Model UKF8001 6-pack of replacement cartridges. The description on Ecolife's web site is somewhat confusing. I found the UKF8001 cartridges, but only for a Maytag french door refrigerator. I could not find one specific to a Whirlpool model. Whirlpool and Maytag are a merged company, and I gambled that the Maytag cartridge would substitute for a Whirlpool. I compared the old cartridge to the Maytag. The connectors are identical, but the Maytag cartridge is thicker. Luckily, I was able to wedge the Maytag cartridge into the water filter holder and close the cover. A more snugger fit, but an adequate replacement for the previous water filter cartridge.