DDS-307A conductivity meter is a necessary instrument for laboratory measurement of conductivity of aqueous solution. The instrument adopts the newly designed shape, large-screen LCD segment code liquid crystal, and the display is clear and beautiful. Instruments are widely used in petrochemical, biological medicine, sewage treatment, environmental monitoring, mining and smelting industries and colleges and research institutions. The conductivity of pure or ultra-pure water in electronic semiconductors, nuclear power industry and power plants can be measured with appropriate constant conductance electrodes.