The Pentek P25-20 filter is used in the following 20 inch Standard size whole house filter systems:

Ametek
Culligan
Pentek
US Filter
Plymouth
The Ametek, Culligan, Pentek, US Filter P25-20, American Plumber W25P-20 20 Inch Whole House Filter Cartridge removes sand, dirt, silt, rust, and scale particles from your household water. The P25-20 is made of spun bonded-polypropylene that is designed for purity and chemical compatibility and will resist chemical and bacterial attack.

The P25-20 is also known as part number P25-20 by Culligan, Ametek, Pentek, Kleen Plus, Plymouth Products, Pentair, Bruner, and US Filter. Part number 155226 Pentek, American Plumber.

The P25-20 Water filter is a replacement for the following parts as well:

Ametek, Culligan, Kleen-Plus, US Filter - P25-20
American Plumber - W25P-20
The Pentek, Ametek P25-20 Specifications:

25 Micron Rating
reduces sand, rust, dirt, silt, scale particles
2 3/8 inches diameter x 20 inches long cartridge
16,000 gallon filter capacity
Temp Range: 40 - 145 F
Flow Rate: 10 GPM @ 0.2 psi
The P25-20 needs to be changed every 4 months and is ideal for use with well water.