I need to replace a cable on a chinese light jobby. My google-fu seems to be failling me though, is there a special name for the 2.5mm barrel connectors that have a shroud/o-ring?

2.5mm DC male. Drop smudge @ mtb batteries an email. He should have some in stock..
Does it look like this:

I thought the plugs vary a touch (between which bits are +ve and -ve)

Nah stevie, its got a shroud on the female end and an o ring on the male (makes the connection pretty waterproof). Not to worry, a mate has a spare apparently.