This Series 3 Halo Portable Wireless Doorbell helps those with a hearing impairment know when someone is at their door.With a maximum volume of 84dB and a choice of digital chimes, it also has a bright LED strobe light which can be used as a visual indicator that the doorbell has been pushed. An additional safety feature is provided by being able to change the chime simply by pressing the button quickly three times which, could be used by friends or family to indicate that they were at the door. The portable chime unit can be placed anywhere in the house within range.