【THREE TYPES】There are three types, cutting fluid testers in different ranges and salinometer that you can choose. Measure salt water or salinity of water, ideal for aquariums and marine monitoring. 【WIDELY APPIICATION】 The salinity refractometer is designed for aquariums, marine monitoring and measures salt water or salinty of water to help you to control concentration of salt water. 【USAGE】 Put 2-3 drops of sample solution after calibration on prism, towards light, then get the accurate readings. The salinity refractometer is ideal for replacement salinity hydrometers or expensive digital salinity tester. 【CONVENIENT TO USE】Saline refractometer is made of fine material, anti-rust, non-staining and resistant abrasion, sturdy for long time use. Convenient to use, handle is comfortable to hold and non-slip.Portable refractometer with plastic case easy to carry. 【HIGH PERFORMANCE】This refractometer features high accuracy and easy operation.A professional measuring instrument, accurate test result. Easy to read by the clear calibration. Convenient to use, handle is comfortable to hold and non-slip.