Ade Advanced Optics Dual Scale 1.0 To 1.070 S.G. Salinity Refractometer For Aquarium & Seawater

This dual scale salinity refractometer is used to measure monitor and control the concentration of salt water and brine. It is especially useful for aquariums and marine applications. This high quality refractometer measures on 2 scales Specific Gravity (D 20/20) and parts per thousand. It can replace your difficult to read hydrometer. Just a couple drops of aquarium water and you know exactly what your salinity is.