Sybon Refractometer with Automatic Temperature Compensation
Hydrometers are not precise enough to measure salinity when very specific conditions must be maintained, such as when maintaining delicate coral and invertebrates or in some breeding situations. The sybon refractometer is used by expert aquarists to obtain the most precise readings possible. Automatic temperature compensation means it reads correctly across a range of temperatures - basically, you can always trust it to be accurate.
Handheld, easy to use and read - simply look through the eyepiece for the measurement