⭐Direct from the Manufacturer - USA⭐ #481234 CONTAINS 1 BOTTLE OF 50 TEST STRIPS FOR MEASURING OZONE LEVELS IN WATER. SenSafe Ozone Check for water quality testing is a unique test strip that is designed to test for levels of Ozone in water. SenSafe Ozone Check gives you accurate results in only 30 seconds. The unique, patented, SenSafe strip allows for low level detection without sacrificing accuracy. Simply dip the test strip into your sample, remove excess water, wait, and read your results using the color matching guide. It's that simple. Reports levels at 0, 0. 05, 0.1, 0.2, 0.3, 0.4, > 0.5 ppm (mg/L), This product DOES NOT require an eXact photometer to read results. 👉👉👉Other oxidizers, including bromine and chlorine, will interfere with results. Contact ITS for an extended test method that uses eXact Strip Glycine ASIN : B00DIJ387W.