About this item Product name Digital Salinity Tester for Salt Water-Waterproof Salinity Meter, suitable for Tester for Seawater, Aquariums, Marine Monitoring, and Koi Fish Pond. Material plastic which is relatively hard and easy to read the salt and specific gravity of your marine aquarium. Size 4.7inx3.5in/120mmx90mm(Length x width) Package contents 1pcs Application The salinity tester can perfectly test the salinity and specific gravity of brackish water and marine fish tanks, including the solubility and specific gravity scale. At the same time, it is very suitable for fresh water and sea water.