Malin Down-Proof Cotton Duvet Insert, 480 GSM Fill

The VoriHaus Cotton Down-Proof Duvet Insert is built around a tightly woven 60/40 cotton shell. Down-proof is a construction term rather than a promise: the weave is tight enough that the fill cannot work its way out through it, which is what keeps feathers inside the duvet and off the sheet. The edges are piped, so the seam is bound rather than simply run closed, and the shell is certified to OEKO-TEX Standard 100.

The fill is a feather and velvet blend at 480 GSM. That is a mid-weight loft: enough to carry a cold night, without the density which makes a heavy winter duvet unusable by spring. It is offered in twin, full, queen, king and Cal king. The supplier does not publish finished dimensions for those sizes, so match the size to your mattress and to the duvet cover you already own rather than to a measurement.

It is machine washable. VoriHaus recommends shaking a new insert out along its length before it goes on the bed so the fill spreads into the corners, airing it rather than washing it whenever airing will do, and keeping it inside a cover, which is what a cover is for: the cover takes the wear and the wash and the insert lasts longer for it. Stored, it wants a breathable bag rather than plastic.