A variety of constructions are available. Most have an internal thermistor or thermocouple or can be connected to external sources. Sampling and measurement are periodically taken and digitally stored. Some have a built in display of data or out-of-tolerance warnings. Data retrieval can be by cable, RFID, wireless systems, etc. They generally are small, battery powered, portable, and equipped with a microprocessor, internal memory for data storage, and sensors. Some data loggers interface with personal computers or smart phones for set-up, control, and analysis. Some include other sensors such as relative humidity, wind, light, etc. Others may record input from GPS devices. Depending on the use, governing quality management systems sometimes require calibration to national standards and compliance with formal verification and validation protocols Manufacturer and distributor Temperature Recorder Temperature Recorder with PRINTER datalogger for Carrier & Thermoking fridge VAN. Temperature sensitive products such as foods,pharmaceuticals,and some chemicals are often monitored during shipment and logistics operations. Exposure to temperatures outside of an acceptable range, for a critical time period, can degrade the product or shorten shelf life. Regulations and contracts make temperature monitoring mandatory for some products.