PR721 series precision digital thermometer adopts intelligent sensor with locking structure, which can be replaced with sensors of different specifications to meet different temperature measurement needs. The supported sensor types include wire-wound platinum resistance, thin-film platinum resistance, thermocouple and humidity sensors, which can automatically identify and load the type, temperature range and correction value of the connected sensor. The thermometer as a whole adopts an aluminum alloy structure, has obtained the national explosion-proof safety certificate (CNEx22.3596X), and has an IP64 protection rating, enabling reliable use in harsh environments.