"Fill power" is a measure of the loft or "fluffiness" of down products and is loosely related to the insulating value of the down. The higher the fill power the more insulating air pockets the down has and the better insulating ability. Also, this makes for a lighter duvet.
A higher fill power means…
· Larger down clusters
· Higher quality
· Lofts higher (fluffier, more billowy)
· Retains loft and firmness longer
· Down came from more mature birds
· Traps more air = better insulating power
· A lighter duvet
750+ fill is quite different from 400 fills. Almost all down commercially available is a secondary product of geese raised for consumption. It would be prohibitively expensive to raise geese for down alone. The geese that are the source for lower fill down are about four months old when they are "harvested" for food. Down from these geese can be carefully sorted, washed, and blended, but it will never loft like really mature down. The 700+ down fill comes from a small number of birds kept for breeding purposes throughout the year. These geese molt naturally in the spring. While their down is loose it is collected by hand. It is very rare and, of course, expensive. The larger individual plumules are what gives the greater loft. The only way to get down of this quality is by careful hand selection which is the major factor in its scarcity.
Beddington's carries many types of down duvets:
