PPM Temperature Waterproof Tester Meter Pen-Type Digital Salinity for Salt Water Pool Aquariums with Temperature In seconds this electronic probe delivers a high accuracy digital reading of the salt content of your water, and even compensates for temperature automatically. And with a reading range from zero up to 999mg/L (ppm) this pen type salt meter keeps going where most others give up Robust and comes complete with a tough carry case and batteries. In fact, any where that salinity in water quality control is important. This compact, salinity tester/meter makes salt spa and swimming pool water testing a breeze. Wide range of applications including salt water aquarium supplies and other water salt content testing. Applications including:Swimming pools and spas,Salt Aquarium supplies,Dam, river and bore water quality,Beverage and food processing,Fish hatcheries,Photography,Laboratory,Schools and colleges.