Contains the 4 basic tests for pool or spa water. Tests for Chlorine, pH, Acid Demand and Total Alkalinity. Clear-view acrylic test block features clearly embossed markings for chlorine ranges reading 0.4,0.6,1.0,1.5,3.0 and pH range of 6.8, 7.2, 7.6, 7.8, 8.2.