Drop-in water filter cartridges are an Industry standard size and will fit all water filter housings of this size including LIFF, Aqua Perfecta, and Pentair to name a few.

When choosing your cartridge please make sure you choose the correct size for your housing.
Industry-standard sizes:

SL10 (2.5" x 10")  BB10 (4.5" x 10") and BB20 (4.5" x 20")

* These sizes are nominal and can be slightly smaller or larger