I've had some for ages, not quite sure what it is they actually 'do' though, other than just look pretty?
(1) If you can wrestle with the little fiddly O-ring and finally prise the bastard thing open enough to get the nozzle of your WD-40 etc can in to the little hole, great.
(2) Then you can marvel in wonder as, reaching for the can of WD-40, you'll find it happily sprays through the hole, WD-40 runs outside the cable outer and drips straight on to the carpet, never coming anywhere near your filthy skanky inner cable.
(3) I find it's altogether quicker and more effective to simply pull the cable outers from the slotted stops – al la old skool way – and do the classic shimmy-shimmy-spray-spray – works every time!
…but they do look pretty.
Or am I just missing something here? 8)