Sometimes it’s nice to be able to test and log several temperatures on a single device. This multiplexer is very useful for the task. Unfortunately you generally glue the thermocouples to whatever you are measuring and they can get broken removing them. If you don’t have a thermocouple welder, which I don’t, you just have to replace them as they break. You can see at the time of this picture, 3 needed to be replaced. Usually there are more than needed so this isn’t a big issue. This device becomes more useful if you have an oven to do elevated environment temperature testing.