Pinpoint Salinity Monitor by American Marine. **** PRODUCT MANUAL **** PINPOINT Salinity Monitor™ will accurately and immediately measure the amount of salt in any marine or freshwater system. The reading is fully temperature compensated, which is difficult or impossible with nearly any commercial hydrometer. The conversion chart will precisely show the corresponding density (specific gravity) or % salt (refractometer) values. This monitor is especially useful to determine the low level of salt required for Koi, whether in an aquarium or outdoor pond. * Given proper care, the PINPOINT Salinity Monitor™ should last a lifetime. * Powered by a standard 9-volt battery (not included).