brand new and high quality. A: PH Tester (one bottle of test solution + one test 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 the standard color card visual colorimetric, the same color tone, that is, the PH value of the water to be tested. B: NO2 Tester (3 test tubes, each can be tested once) Instructions: 1. Take one of the reagent bottles, the bottle mouth is up, gently vibrate, 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 the standard color card visual colorimetric, the same color tone, that is, the nitrite content of the water to be tested (mg / L) C: NO3 Tester (3 test tubes, each can be tested once) Instructions: 1. Take one of the reagent bottles, the bottle mouth is up, gently vibrate, 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 the standard color card visual colorimetric, the same color tone, which is the nitrate content of the water to be tested (mg / L) D: Chlorine Tester (one bottle of test solution + one test tube) Instructions: 1. Open the stopper, add water to the mark line, drop a drop of test solution, cover the stopper, and shake up and down to mix evenly. 2, from top to bottom and the standard color card visual colorimetric, the same color tone, that is, the content of free chlorine in 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 content of total chlorine in tap water after dechlorination is 0. Note: When testing, try to compare colors when the light is good. If the test reagent is accidentally splashed on your eyes or skin during the test, it should be rinsed immediately with water. This series of detection reagents is toxic and should be placed in a place that children cannot for touch. Please allow 1-3cm error due to manual measurement. please make sure you do not 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 includes: 1set Water Test Reagent