[Completely waterproof] The battery compartment is sealed against accidental splashing or brief submersion under one meter of water or plant food. No external knobs or switches. [Completely waterproof] The battery compartment is sealed against accidental splashing or brief submersion under one meter of water or plant food. No external knobs or switches. [Function] Nutrient meter measures EC (electrical conductivity), CF (conductivity factor) and PPM (parts per million) scales. High conductivity measurement for a broad range of crops. [Accurate readings] Accurate readings every time-truncheon is factory calibrated (further calibrations can be carried out easily with EC 1.4 buffer solution on regular basis to keep accuracy). [Auto turn on and off function] The nutrition analyzer is beautiful in appearance, easy to use, with auto turn on and off function which activates truncheon when put in to, or taken out of solution. [Usage Method ] 1. Place the head of the probe into the solution for 1-2 minutes so that the temperature of the probe and the liquid are the same. Remove probe. 2. Place the probe back into the solution. The LED lights will indicate the nutrient levels 3. Rinse probe and replace cover. That's it!