These Poolmaster Smart Test 4-Way Test Strips are ideal for maintaining your pool/spa's proper water chemistry. They are easy to use and read. Simply dip the pool test strips and read for instant results. Color indicators on the strips react to the water's chemistry. Match the color indicator on the strip with the chart for comparison. These Poolmaster test strips analyze four chemical factors including free chlorine, bromine, alkalinity and pH. They come in an easy to store container package with 50 strips.