The Pipe Range Extender is designed to measure the temperature of a metal pipe, while at the same time get maximum radio range (it is a variant of the Surface Range Extender).
Placing a sensor flat on a metal pipe gives a very good measurement of the pipe temperature, but as metal absorbs a lot of the radio frequency (RF) energy, the radio range is severely degraded.
The Pipe Range Extender solves this by the use of a range extender embedded in a sensor accessory. The sensor is placed on the pipe, with the range extender lifted up from the metal pipe. This design allows the radio waves to propagate better, hence achieving maximum range combined with great thermal coupling to the surface for accurate temperature measurements.