Hot Water Bottle Large Classic Non Toxic Natural Rubber Bag with Heart Red Knit Cover, 2L Pain Relief from Sore Muscle Cramps Injuries Back Pain Warm Cold Therapy, 1/2 Gallon;

The heat of hot water bottle can keep more than 6 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.