With the push of a button, this device can tell you your water safety level, which will be displayed on a screen. The lower the TDS level, the pure is the water. This tool made of the super quality material is a great tool for water filtration and purification, aquariums, pools, spas, and more. It is white in color and has a body made of plastic. Although the case of the tester is made of leather and is black in color. It is highly efficient and accurate due to its advanced microprocessor technology. Wasser Digital TDS Meter Water Purity Tester with Leather Carry Case and Temperature Display- Designed in Tokyo saves measurements for convenient reading and recording TDS = Total Dissolved Solids, which is any salt, metal or mineral in the water. With the push of a button, this TDS can tell you your overall water purity level, which will be displayed on the screen in ppm (parts per million). The lower the TDS level, the purer the water, with 0 ppm being pure H2O.(The meter does not test for biological contaminants). It is the world's most popular handheld TDS meter for both industry professionals and house hold use.