In reply to nb290:
I've no idea on the first point, as I don't know the technicalities of it all, all I know is that it just works.
As far as freezing goes, I've only used it since early summer so I haven't had that problem yet, but yes I suppose some kind of insulation may be needed. However, yes it does have various different bottle attachments so it wouldn't surprise me if one of them fits either a Platypus or Camelbak.