RISEPRO Salinity Refractometer, Aquarium and Salty Sea Water Pool Dual Scale Hydrometer 0-100ppt & 1.000-1.070 Salinity Specific Gravity Marine Fishkeeping ATC RHS-10ATC MONITOR SALINITY LEVEL  RISEPRO R Refractometer can measure the salinity of your salty solution. Perfect for salty water tank and aquarium, seafood water tank, salty pools & spas and etc. HIGH QUALITY CASING  This refractometer is made with sturdy and light weighted aluminum casing with high quality finish. Assure of long durability and heavy duty usages! EASY TO MEASURE WITH DUAL SCALES  All you need to do is place 2 - 3 drops of sample onto the prism, and then look through the eyepiece for both Salinity level in PPT and Specific Gravity in D 20/20. MEASUREMENT RANGE : Salinity 0  100 PPT with resolution 1PPT ; Specific Gravity (D 20/20) : 1.000 ~ 1.070 with resolution 0.001 HIGHLY ACCURATE WITH ATC  The accuracy level is Salinity : +/- 1ppt (0.1%) and Specific Gravity : 0.001. Automatic Temperature Compensation range is from10 C to 30 C.