This product is a must have if you use salt in your Koi Pond.  Simply turn on and dip this very accurate and easy to use salinity meter into the water and within seconds the LCD display will give salt content in percentage.  It features auto shutoff, drop shock to 6 feet, 150 hour battery life, low battery warning and it is water resistant.  Meter comes with 4 each 1.5volt button cell batteries.