Your Lab-Aids® 9 Level Conductivity Meter is well constructed. When treated with proper care and concern it will provide you with many hours of satisfactory service. The Lab-Aids® 9 Level Conductivity Meter shows the relative conductivity/resistance of liquids and solids. As the conductivity of the tested material increases, the number of glowing red LEDs (light emitting diodes) will increase to a maximum of 8, which indicates a very good conductor. There will be zero glowing red LEDs if the material being tested has a very low electrical conductivity (is a good insulator).