Cycle Trailer-cum-dry bag-with-wheels thingy?

Doing some trailer research, and I remember that there used to exist one (from Edinburgh cycles I thought?) that was to all appearanes just a drysac with hitch, internal frame and wheels attached; the wheels were detachable and could then be stored in pockets in/on the drysac itself.

I can't find this anywhere online, does anyone know what I'm talking about (oh, how often have I asked that...) and where it's available if at all?

I'm leaning towards an Extrawheel, but I'd like to have a look at this one if it's not a figment of my imagination...