Ideal for those who have already purchased the AquaChek Select kit and just need additional test strips. A replacement color chart is enclosed with every bottle for insertion in the reusable color comparator. Get 7 important test results in just one dip!  Dip an AquaChek Select strip in your pool or spa water for one second and remove it immediately. You get test results in seconds! To keep you pool water clean and healthy, test the water at two ends or sides of the pool a minimum of twice a week!  If used in a spa we recommend testing it before and after each use.  It's also a good idea to write down your results each time you test. Tests for 7 important chemistries in seconds: Total Chlorine, Total Bromine, Free Chlorine, pH, Total Alkalinity, Total Hardness and Cyanuric Acid (Stabilizer). 2 pack includes two sets of 50 strips.