ZDS- EC Pen Check WP Range: 0.00-19.99 EC(mS/cm), Resolution: 0.01 EC, Accuracy: ¡À2% Full Scale, Battery Life: DC4 x 1.5V, Temp.¡æ: 5--50¡æ (ATC), Features: Automatic switch-off function: After 8-10 minutes without pushing buttons, the meter will be switched off automatically.