Direct from the Manufacturer - USA SenSafe Iodine Test Strips #480018 CONTAINS 1 BOTTLE OF 50 TESTS FOR MEASURING IODINE LEVELS IN WATER. SenSafe Iodine Test Strips test for a broad range of concentrations from 0. 02 to 5. 0 ppm(mg/L). With such a wide range, these test strips are ideal for the food and medical industries, as well as water treatment use. Accurate results can be obtained quickly. Simply dip the strip into your water sample according to the instructions provided, remove the strip, and read your results. The unique, patented, SenSafe strip allows for low level detection without sacrificing accuracy. This product is safe and easy to use since there are no chemicals to mix, an MSDS is not required, and the indicator is noncarcinogenic. Method A detects Iodine levels of 0. 0, 0. 5, 1. 0, 2. 0, 3. 0, 4. 0, 5. 0 ppm (mg/L). Method B detects Iodine levels of 0. 00, 0. 02, 0. 05, 0. 10, 0. 20, 0. 30, 0. 40 ppm (mg/L). This product DOES NOT require an eXact photometer to read results.