Handheld temperature meters have digital displays that show temperature readings. They have one or more connections for compatible temperature probes. High-accuracy thermistor meters are handheld instruments that measure suction- and liquid-line temperatures and evaporator coils and ambient temperatures. Long-life and high-accuracy RTD meters use an external probe to record measurements and check and perform temperature calibrations. Wide-application thermocouple meters measure contact temperature inputs on motors, insulation, breakers, pipes, corroded connections, and liquids and wires. Multi-channel handheld meters use many compatible probes to measure different samples simultaneously.