The silicone stopper ensures that steam escapes properly to limit heating of the glass neck
Silicone rubber ball steam stopper
Perfect balance of form and function
"The CHEMEX Carafe Kettle, the smart choice for boiling water, performs as beautifully as it looks. Made of heat-resistant glass and scientiï¬cally designed, our elegant kettle shape and silicone tipped steam diverter will by a show stopper in ay home.  The kettle's non-porous glass imparts no flavors of its own, making it the perfect beverage server for your preferred drink."  "The Handblown water kettle may be placed directly on a gas flame, glass top or ceramic top stove.  For use on an electric stove top please use our wire grid (TKG) to safely boil water.  Please use a cloth or glove when removing kettle from stove top as the neck may be warm."