This duvet is made with soft, plush microfiber fill, a high quality polyester that's meant to mimic the softness of down. The shell is a crisp, durable 260 thread count cotton.
Microfiber doesn't have the same insulating properties as down, so microfiber duvets are heavier weight. A fair bit of fill is required to achieve the desired warmth. One benefit of a synthetic duvet is that it can be machine washed at home, given your machine is quite large and you wash/dry on a low heat setting. Natural down and feather are sensitive to moisture, but polyester is not!