The RT801 is a great low-cost alarm thermometer. Perfect for monitoring refrigerators, freezers, coolers, chillers and all other types of cold storage systems. It's also great for aquariums, terrariums, incubators, and hundreds of other uses wherever you want to make sure an acceptable temperature range is maintained. Simply set the desired high and low alarm temperatures and position the external probe in place and you've got a monitoring system for your critical environment. Use it as a safety alarm or to notify you when a desired target temperature is reached.