Lactometer is a little glass instrument used to measure amount of water in milk you drink. Lactometer works on the principle of the specific gravity of milk. It is a small device which is very easy to use and gives accurate results less than a minute. Now, you can test the quality of milk in seconds with this premum quality lactometer and make sure that you are getting pure milk without added water. How to use? Put milk in test tube. Insert meter in the tube with bulb downwards. Check reading on meter. Milk level up to red marking indicates pure milk. Or Milk level above red marking indicates impure milk. The deeper the meter sinks in the tube the more impure the milk is.