A horse standing in a chilly stable during the winter will probably feel the cold more in this static position than he would outdoors where he is free to move around. He will therefore appreciate having a quilted stable rug to keep him warm and cosy while he's tucked up in his stall for the night, particularly if he has been clipped.
Stable rugs do not need to be as thick, heavy or waterproof as turnout rugs. In fact, they are specially designed not just to be more lightweight than turnout rugs, but are also looser fitting, to allow comfort for the horse while sleeping.
Choose a stable rug with an integrated neck cover for extra warmth and comfort.