From the product description, check product page for current description, price and availability:

You likely want to monitor the temperature of your wort as it moves from the chiller to the fermenter, and now you can do just that with this In-Line Thermometer. This high quality thermometer features stainless steel quick disconnects for easy installation in line with the rest of your brewing system, and many users install it on the “out” side of their convoluted heat exchangers and counterflow chillers.

As the wort runs through the body of the in-line thermometer it runs across the 2-inch thermometer probe, giving an instant and incredibly accurate reading of its exact temperature. Ryan Barto, our Fulfillment Operations Manager and also the thermometer’s inventor, says that this handy device will help you to keep better control of your mash temperatures, and makes it easier to transfer your wort to your conical through the counterflow chiller.