Have you ever heard of PLA' For those who haven’t it stands for Power Line Adaptors.
This technology consists of integrating a high frequency signal into your electrical network. For France this signal was set to 50 Hz, but for High Speed (like the 200 Mbit/s offered in the HDX-101) the signal frequency was between 1.6 and 30 MHz making it previously possible to obtain either 14 Mbit/s (with the XE104) or 85 Mbit/s (with the WGX102). Now the frequencies that will be used are set between 9 and 150 KHz in Europe and 150 and 450 KHz in the United States.
This allows you to install a high speed network of good quality by using the electricity cables already present in your home or office, meaning that you no longer need to run Ethernet cables around the walls, or to invest in an expensive wireless solution - where the speeds are not guaranteed due to the limitation of your houses walls and the distances between devices.

The pack for sale by NETGEAR under the HDX101 name contains an adapter and a one and a half meter RJ45 cable, along with the setup guide, drivers and other documentation (stating how easy it is to install these adapters).
To create a PLA network, you will need at least two HDX101 adaptors, and in the event you want to share an internet connection then you will also require a modem, router or other connection sharing device which can be used to share the Internet Connection.
For a local area network without a connection to the outside world, the adaptors can be used as they are and the electricity network will act as your hub.