Check the listing for details. 4Pcs PH Test Strips 80 Litmus Indicator Papers Tester Alkaline Testing Red. Condition: New. Listed at 14.68 USD. Litmus papers are used to determine the pH level of a liquid and determine if a solution is basic. Widely used for industrial chemical testing, science education, laboratory use, drinking water, aquariums, and classroom analytical chemistry.SpecificationTesting Paper Size: 54mmx9mm (L*W)Overall Size: 70mmx45mmx5mm (L*W*H)Packing List: 4 x Litmus Test Kit (80/Pack,320pcs)AdvantageCan be used to determine the strength of acid and base conveniently. Sensitive to the environment and temperature changes.InstructionDipping the test paper into a solution and observing the change in color of the paper. After one second read the pH value. If the test paper turns blue, the solution is alkaline.NOTENot applicable for oil and acid-base solutions with a concentration of less than 0.01%. Should be stored in a dry place protected from light.