New name! New label! Same easy to use meter! Now with the 4 most popular scales: EC, CF, 500:1ppm, and 700:1ppm! The E.C. Dipstick dissolved salts pen operates on 3 common inexpensive AA alkaline batteries. Measures in PPM, EC and CF scales. There is no calibration required. It calibrates itself each time you replace the batteries. It is water resistant so a light emersion in the plant nutrient should not hurt. However, it is a good idea to test small amounts of nutrient away from large bodies of water just in case you have butter fingers.