17S test: There are 2 test strips for underwater dipping pools, keep about 15 in the air, then match the color of the strip to the color on the back of the bottle, which takes about 17 seconds. Swimming pool test strips are easy to use and suitable even for beginners.6 inch (about 6 cm) 1 liter upgrade: test pH, total chlorine, no chlorine, total alkalinity , acid purification, total hardness, etc., more powerful than 5 or 4 swimming pool test panels and liquid test toolsHealth: The test strips are used for analysis of the water from swimming pools, spas and hot tubs, and you can ensure the right amount of chemicals are kept in the pool to prevent health issues and equipment damage.Easy to carry: size about 3.9*1.6 inchEnvironmental protection: The pool water quality should be tested weekly. A pack of test strips includes 50 test strips and pool seals, 5 moisture-proof packaging to ensure long-term storage.