Natural rubber hot water bottle retains heat for a long time. Cap with natural rubber seal. Double glazed to allow a gradual combination to heat. Also contains a soft cover. Unscrew the cap, fill the bottle with hot non-boiling water up to 2/3 of the capacity (1,100 l). Empty the bag completely from the air by gently squeezing it on a flat surface until water appears from the mouth. Screw the cap back on and place the bag where you want to apply.