The world's favourite nutrient meter! With its super tough, high quality, fully waterproof design, no calibration required, daylight readable blue LED's and no on/off buttons to worry about, the Bluelab Truncheon® Nutrient Meter has proven itself as the world's favourite nutrient meter. It is essential when growing with a hydroponic solution to KNOW what the strength of the solution is before feeding your plants AND while they are growing. This is easy if you use the Bluelab Truncheon! To take a reading of your solution - simply place the probe head into the solution for 1-2 minutes to reach the same temperature of your nutrient. Remove from the solution and place back in to take the reading as indicated by the flashing lights. Rinse the probe after use in fresh water and clean once a week to ensure the Truncheon Nutrient Meter remains accurate. Calibration of the Meter is not required and it's great for stirring your nutrient tank too! Main Features: - EC (0.2 - 3.6), CF (2 - 36) and ppm scales (TDS and 700 scale) - Fully waterproof - No calibration required - Auto sense on and off - No external switches or adjustable buttons - Battery life minimum 1 year (or shelf life of battery)