They are cat5/6 Ethernet with RJ45 connectors.
Originally Posted by Meridian SpeakerLink data sheet
What cables do I need?
No cables are supplied with the product as you can use standard Ethernet cabling as long as it is STP (Shielded Twisted Pair) CAT 5 or 6 cable.
You may need to meet additional standards when installing cable in-wall, but as far as SpeakerLink is concerned, CAT 5/6 STP is all there is to it.