If your BeoLab or BeoSound Core/Moment/ or TV has the connection as shown in the picture, you will need the RJ45 powerlink cable.
You can find that cable here.
You can also take the cat7 cabling which is specific for these connections.
Suppose you have speakers with a round Din connection, but your TV or BeoSound has an RJ45 connection?
Than you can connect with RJ45 to DIN8 cable.
You can also connect from RJ45 to din8 female, existing DIN8 cables via short adapter cable.
even a splitter from RJ45 to 2 x DIN8 is possible.