. A: ph tester (one bottle of test solution + one tube) Instructions: 1. Open the stopper, add water to the mark line, drop 2 drops of test solution, cover the stopper and shake up and down to mix evenly. 2, From top to bottom and standard color card visual colorimetric, the same color shade, that is, the pH value of the water to test. B: NO2 Tester (3 tubes, each can be tested once) Instructions: 1. Take one of the reagent bottle, the mouth of the bottle is up, vibrate gently to make the powder at the bottom of the bottle. 2. Open the stopper, add water to the mark line, cover the stopper, and shake up and down to make the mixture even. 3, placed for about 10 minutes, from top to bottom and standard color chart visual colorimetric, the same color shade, that is, nitrite content of the test water (mg/L) C: NO3 tester (3 tubes, each can be tested once) Instructions: 1. Take one of the reagent bottles, the mouth of the bottle is up, vibrate gently so that the powder is at the bottom of the bottle. 2. Open the stopper, add water to the mark line, cover the stopper, and shake up and down to make the mixture even. 3, placed for about 10 minutes, from top to bottom and standard color chart visual colorimetric, the same color shade which is the content of water nitrate to be tested (mg/L) D: chlorine tester (one bottle of test solution + one tube) Instructions: 1. Open the cap, add water to the mark line, drop a drop of test solution, cover the stopper and shake up and down, to mix evenly. 2, Top to bottom and standard color card visual colorimetric, the same color shade, that is, the free chlorine content of the water to be tested (mg/L) 3. After placing for about 10 minutes, read the colorimetric again. The value read is the total residual chlorine content (mg/L). 4. The total chlorine content of tap water after dechlorination is 0. Note: When testing, try to compare colors when the light is good. If the test reagent is accidentally sprayed on the eyes or skin during testing, it should be rinsed immediately with water. This series of detection reagents is toxic and should be placed in a place that children cannot touch. Please allow 1-3cm error due to manual measurement. Make sure you don't mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package Included: 1 Set × Reagent Water Test