Insta-Test Biguanide 4-way test strips allows the user to just dip the strip into the water and receive accurate results. The formula is designed for stable color development to allow adequate time for the user to match very distinct colors along with preventing cross-contamination between pads. Insta-Test Biguanide 4-way test strip measures Biguanide (0 - 80 ppm), pH (6.2 - 9.0) and Total Hardness (0 - 800 ppm). The waterproof pop-top bottle with desiccant liner protects the strips from moisture intrusion. There are 25 strips per bottle.