Made of natural rubber Resistant to boiling water 100% leak proof ... , such as copperVol / size300ml – 2000mlFeature1, First grade natural rubber hot water bottle,2, Resistant to boiling water; 3, 100% leak ... detection test.The hot water bag is made of by Natural Rubber material, also can with kinds of cover, ... , especially rigid and sharp things. BS1970:2006 Standard Natural Rubber Hot Water Bottle