The RTR-500 data logging system from TandD Corp., Saratoga Springs, NY, lets you monitor and download data without having to physically retrieve the loggers. the RTR-500 is a wireless base station that connects to a PC through a USB port and can function as a base station or as a repeater. The RTR-501 logger can be used indoors or outdoors and has an internal sensor with a –40°C to 80°C range. The RTR-502 has a variety of optional external sensors and a measurement range of –60°C to 155°C. The RTR-503 also has an external sensor that measures temperature from 0°C–55°C and 10%–95% RH. Transmission range is 500 ft. LOS.