The double-walled housing creates an air chamber between the inner stainless steel container and the outer plastic wall, which ensures that the temperature inside is stored longer and at the same time ensures that the outer wall is kept cooler, even immediately after boiling. The outer housing becomes warm, but not so hot that burns can occur when touched. However, it should be taken into account that all people have a different perception of warmth. Therefore, caution is required when handling heated devices.