Apera Instruments PC60 Premium 5-in-1 Waterproof pH/Conductivity/TDS/Salinity/Temp. Multi-Parameter Pocket Tester, Replaceable Probe Simultaneously tests pH/EC/TDS/Salinity/Temp. in a quick,accurate, and reliable manner EASY-TO-INSTALL Replaceable Multi-parameter Probe with EASY measuring mode switch Auto recognition of stable values (with optional AUTO HOLD function) improves consistency so you dont have to guess when to manually hold measurement LARGE CLEAR viewing angle screen with 3 backlit color (indicating 3 different modes), dual display of temp./pH/EC/TDS/Salinity, and indications of completed calibrations and stable readings COMPLETE KIT with READY-TO-USE calibration solutions, calibration bottles, storage solutions, AAA batteries, and a lanyard all in a portable carrying case