Description:Designed to measure salt water. For home, or professional use. Measures the specific gravity of water or salinity by determining how the liquid affects the bending of light through a prism. Main Features:● Designed for testing the concentration of salt water and brine● Ideal for aquariums, marine monitoring and quality control in research and clinical laboratories● Features automatic temperature compensation ( ATC )● With soft rubber eye piece for comfortable viewing● Soft silicone handle provides good touching feeling● Uses ambient light only which means battery or power source is not required Special function: Salinity Refractometer Package weight: 0.300 kg Product size (L x W x H): 19.40 x 4.00 x 2.00 cm / 7.64 x 1.57 x 0.79 inches Package size (L x W x H): 21.50 x 8.50 x 6.50 cm / 8.46 x 3.35 x 2.56 inches Package Contents: 1 x Refractometer, 1 x Screw Driver, 1 x Suction Tube, 1 x Wipe Cloth, 1 x Carrying Case, 1 x English User Manual