There are 2 types, with & without backlight, choose based on your needs Small size, portable, you can carry it with you wherever you go Can measure ORP,, and Temp value with high at the same for time With data hold, ℃ / °F switchable function, built-in 3x1.5V button battery for Ideal for household and laboratory testing applications, including drinking water, swimming pool, pond, aquariums, Manufacturer: Whoasyst