Almost all modern Bang and Olufsen Beolab active speakers (ie. those powered from the mains supply) should be connected to your audio system or television using Powerlink cables. These are all similar in outer appearance, with a round 8-pin DIN plug at each end of the cable. However, there are three versions of this cable:-
Powerlink mark 1 is the simplest type and can be used by most older Beolab speakers, including Beolab 1, Beolab 2500, Beolab 4000, Beolab 6000 and Beolab 8000. I usually recommend using mark 3 cable instead of mark 1 - see below for the reason why. Powerlink mark 2 (also known as "fully wired") is for speakers with built-in displays, including Beolab Penta (mark 2 and 3 models only) and Beolab 3000, 4500 and 5000 panel speakers. This is also required for use with Beolab 5 speakers. This cable will also work with all other Beolab speakers with Powerlink connections, so it is the best version to choose if you are likely to change your speakers in future. Powerlink mk.3 is the latest version for the ICE-Power Beolab speakers with class D digital amplifiers, as it contains an additional voltage reference wire intended to prevent background hum. This is for Beolab 2, Beolab 3, Beolab 4, Beolab 7.1, Beolab 7.2, Beolab 9, Beolab 10, Beolab 11, Beolab 4000 mk.2, Beolab 6002 and Beolab 8002. This can also be used to replace mark 1 cable, so any of the speakers listed for use with mark 1 cable can also be used with mark 3 cable.
The older mark 1 cables are best avoided in most situations, as they offer no advantages but they are incompatible with many speakers from the current Beolab range.
The exceptions to the rules above are the very earliest Beolab speakers (notably the Beolab Penta mark 1), which used a special connection type called Speakerlink. This used a specially made plug, which has not been manufactured since the late 1990's. However, a 2-pin DIN speaker cable can be used to power these speakers, although the displays will not light up.
B&O also built a couple of "link room" speakers (Beolab 2000 and 3500) which use Masterlink cables instead of Powerlink.
Steve at Sounds Heavenly