Test strips suitable for the detection of chlorine and nitrite. Gradations: 0 - 2 - 8 - 25 - 70 - 100 ppm free chlorine (the pH of the test solution should be around neutral). Gradations: 0 - 2 - 5 - 15 - 30 - 100 ppm nitrite (the pH of the test solution should be less than 2).