DOUBLE CHECK - Each tester strip is designed with two identical color pads. If the color of the pads differs after testing, it indicates that the test may not be reliable and a new test should be performed. | SAMPLE CUP INCLUDED - Ensure the most accurate water hardness tester results by using the included, free sample cup and fill the testing water to the marked level. | 200 WATER TEST STRIPS @ $0.04 EACH - Maximize the time between each purchase with the lowest cost-per-test water hardness test strips that are available. | LONGEST SHELF LIFE - Individually wrapped in packs of 50 to prevent unused strips from going bad due to too much contact with air. Dual, top-and-bottom desiccant design forms a dry force shield around the strips which also prevents the strips from going bad due to too much contact with moisture. | EASILY THE MOST ACCURATE - DoubleCheck to weed out bad color pads, sample cup with pre-measured water level for the most optimum water to test strip ratio, individually wrapped and dual desiccant design gives more accurate results for a longer period of time.