AQUAPAPA Large 1/2 Gallon Classic Non Toxic Natural Rubber Hot Water Bottle with Snow Flake Knit Cover, Back Pain Relief, Cold Feet Syndrome, 2 Liters;

The heat of hot water bottle can keep more than 8 hours if you use it in blanket or quilt. It always depends on the environment you use it. As with the knit cover, you may not feel very hot. If you like hot feel, please remove the cover to get more heat.