The Truncheon Meter from Bluelab instruments is the best selling hydroponics CF/EC Meter in the world. This Truncheon nutrient meter measures EC, CF & and PPM scales. This EC meter is factory calibrated, fully waterproof and has auto turn on and off. This truncheon meter is powered by three standard AA batteries (not included). There are no external switches or adjustment knobs on this EC Truncheon Meter. Why do growers prefer the Truncheon? It's easy to use, easy to read, extremely accurate and best of all its reliable. The Truncheon EC Meter will last for years. Includes instruction manual and carrying handle.