Through the introduction of this article, I hope you know more about the hot water bottle. And for a better heat insulation effect, they must be equipped with a suitable Hot Water Bag Cover. There are many different kinds of materials for the cover, which all have different characteristics, such as Knitted Hot Water Bottle Cover, Fur Hot Water Bottle Cover, Fleece Hot Water Bottle Cover, Animal Hot Water Bottle Cover, etc. http://www.hollywarm.com/hot-water-bag-cover/knitted-hot-water-bottle-cover/