3-in-1 Test Strip: The pool chemical test strip can test 3 parameters: pH, free chlorine, bromine, and total alkalinity. Extremely Accurate: The pool and spa test strips are made of high-quality imported filter paper with 6 color indications on each strip to display high accuracy and reliable instant readings. [Packaging and Dimensions] Our test strips have separate waterproof bags to ensure long-term storage. 9.5 x 3.5 x 3.5 cm (approx.), easy to carry. The quality of the swimming pool water should be tested once a week. [Usage] Dip the test paper into the water for 2 seconds, let it stand in the air for about 15 seconds, and then match the color of the strip on the back of the bottle. In just 17 seconds, you can read the data. [application site] Pool water test strips can help you test the water chemistry of swimming pools, spas, and hot tubs to keep your pool water healthy and clean.