The unique, patented design of red Sea's hydrometer enables it to be installed inside the aquarium or sump. Giving a continuous "real time" reading of specific gravity. In addition it can be used as a typical hydrometer for periodic measurements.
Includes a digital thermometer to insure tested water is at correct temperature.
Part #: ARE12010 Item Name: Red Sea Hydrometer With Digital Thermometer ID: 6569-pid