In fact, the designer Haishan Deng invented this doorknob so that you could call for help if you slipped in the bathroom. The timer is set for a specific time and if it is not turned off in time, the alarm will first ring, and then the system will ring back to the pre-programmed telephone number. The concept is relevant for older people, as well as overly clean wives (we have one who loves hanging around in the bath for days).