No matter what your application, WaterWorks pH Check for water quality testing is the convenient measurement tool for accurate, rapid pH detection in tap water, process water and control, ponds, lakes, and streams. Utilizing a dual-pad indicator system is what makes this pH test unique. Both indicators are designed to work in unison, providing a wide range of color development. Additionally, the dual-indicator system makes color matching easier and more reliable since both colors are uniquely different from each other. With its wide range of detection, low cost per test, and safe chemistry, WaterWorks pH Check is the ideal choice for fast, accurate pH detection you can trust. Number of Tests: 1 Sensitivity: 2, 3, 4, 5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12 Total Test Time: 30 Seconds Compatible Brita Drinking Water Carbon Block Under Sink Replacement Filter USF-104 Compatible with most national brands such as: Dupont, Whirlpool, Omni, GE Model USF-104 (fits system USS-120) 10" x 2.5" Carbon Block in 0.5 Micron Filters up to 1,000 Gal. or lasts for 6 months.