The Bluelab BLU2000E Truncheon nutrient meter is an essential tool in hydroponics, horticulture, and floriculture for measuring the concentrations of solutions before feeding and while plants are growing. This meter measures EC and CF units on the 500 and 700 PPM scales. To take a reading of the solution, simply place the waterproof probe into the solution for 1 to 2 minutes to allow the probe to reach the same temperature as the nutrients. The reading is indicated by blue LED lights and is accurate to within + or - 4%, while the meter's automatic ON/OFF function prolongs the life of the batteries. Complete with a 5-year warranty, this meter will ensure your next grow project is a success. Includes three AA batteries.