Culligan S1A Level 2 Extra Filtration Sediment Replacement Cartridge, 2pk: * Fits models HF-150A, HF-160 and HF-360 * 20 micron spun resin-impregnated cellulose cartridge * Reduces: sediment, rust, scale, dirt, coarse sand, sand and silt * Not recommended for use with non-treated well water supplies * Cartridge life is up to 4 months or 16,000 gallons * Cartridge change reminder sticker included * Model# S1A