For the best results this season, use Insta-Test 4 Chlorine Test Strips to tell what you need in order to properly balance your water. Insta-Test strips help to provide an understanding of your waters safety to ensure your family and friends get a clean and clear aquatic atmosphere to enjoy. These strips will check your pool waters Free Chlorine, Alkalinity, Cyanuric Acid (stabilizer) and pH in just a matter of seconds! These test strips are specifically designed for swimming pool water and come in a pack of 50 so you can always make sure you're water is safe to swim in. The convenient close cap bottle top allows you to secure the strips so they don't wet get. With these strips, it's as easy as dip and read!