This hydrometer is molded from clear acrylic and uses a swing-arm pointer to indicate specific gravity and salinity levels in marine or brackish aquarium water. Specific gravity is read on an inside scale spanning 1.000 to 1.030, while a corresponding outside scale shows salinity in parts per thousand, with a color-blocked zone marking the typical range used in reef and marine setups. An extra-wide stabilizer base keeps the unit steady on a flat surface while a reading is taken, and a corner fill port lets the chamber be filled by dipping it below the water line without submerging hands. The device is temperature-corrected for accurate readings in water between 68 and 85 degrees Fahrenheit. No batteries, power source, or calibration fluid are required for operation. Rinsing after each use and an occasional soak in a mild acid solution such as vinegar help clear mineral and salt deposits that can otherwise skew the pointer's reading over time.