This Refractometer is an incredibly accurate and easy to use device that eliminates the confusion associated with inexpensive hydrometers. Just place a couple of drops of water on the prism and hold to the light. Reads in percent and specific gravity. An absolute must for the serious marine hobbyist.
Refractometer is an optical device (no batteries required)
Dual scaled 0-100%
Specific gravity: 1.0 to 1.070
Calibrate with distilled water
Carrying case, pipette and calibration screw driver included.