Swimming Pool Residual Chlorine Test Paper Strip. Features: It is Widely Used in the Processing of Drinking Water and Tap Water, Food Processing, Laboratory Operation, Environmental Analysis, Aquaculture, Industrial and Agricultural Water and Other Fields. Easy Operation, the Visual Colorimetric Method is Used to Measure. Fast and Efficient Seconds Can Be Ended, Fast and Efficient. Small in Size, Light in Weight and Convenient to Carry. Used in Swimming Pools, Spas, Hot Tub Etc. It Can't Measure Tap Water and Purified Water. Chlorine Test Strips Only, Other Accessories Demo in the Picture is Not Included. Instructions: Take a Test Strip Directly, Put the End of the Color Block into the Solution to Be Tested, Take It out Immediately, and Compare It with the Color Card Within 15 Seconds. SPECIFICATIONS: Material: Test Paper Size: App.10.5x3.5cm/4.13x1.38in Color: As Pictures Shown Quantity: 1 Bottle (50pcs) Package Contents: 1 Bottle X Chlorine Test Strips