Not sure if this is it:
I bought some once with zips on from Germany, they soon ended up in the bin as zips on duvet covers tend to break really easily.
I bought a down comforter years ago and have just bought "duvet" covers when I changed my color scheme and I bleach it once a week to make sure that it has no mites, or anything growing in there. It is white and bleachable and i would recommend you d...