This kettle is equipped with the special SIGMA Classic base is made of a precision press, which is always identical on ZWILLING cookware. It ensures excellent heat distribution and storage. This whistling kettle which heats up to 1.5 litres of water, guarantees a fast boil and retaining the temperature as long as possible. Besides retaining heat, the kettle retains cold temperature very well. The in-built whistling function which creates a subtle but noticeable sound once water begins boiling and reaches the perfect temperatur. This is a safety measure to avoid over spilling or accidents. The sturdy handle is made out of an excellent synthetic material which you can directly hold to pour the boiled water out.