Here's an automatic, temperature-compensated salinity refractometer. It's the low-cost alternative to the SR6.
It has automatic temperature correction from 50–86ºF (10–30ºC) and a dual scale reading 0–100 ppt and 1.000–1.070 specific gravity. Each refractometer is tested to ensure an accurate instrument, even at this low price. Six-month warranty. Weighs .6 lb. Made in China.