AO Smith Whole House Water Sediment Filter - Valve-in-Head Single-Stage Filtration System - NSF Certified - AO-WH-PREVBrand: AO Smith Color: White Features: Sediment Prevention The AO WHO PREV system is certified to reduce sediment, dirt and rust in your water, applicances and plumbing fixtures. Designed to bring you sediment free water from every tap in your home. Easy Filter Replacement The built in shut off bypass valve allows you to change filters witout turning off your water supply, and the pressure release button allows for quick, easy filter replacements.