1、Excellent Speaker: This doorbell adopts excellent speaker, with closed sound source isolation structure to avoid the speaker shaking and breaking sound, and the sound is more pleasing to the ear. 2、Mute Mode: This doorbell can be set to silent mode, only the LED light flashes to remind, and will not ring to disturb the family rest. 3、Power Failure Memory: This doorbell adopts memory chip, when power failure or replugging ringing, it automatically restores to the set ringtone, without the need to repeat the setting. 4、IPX4 Button: This doorbell features IPX4 buttons that are rain and shine proof and can be installed outdoors, rain and shine free. 5、Wide Application: This doorbell has a very wide range of applications and can be used in homes, apartments, villas, offices and hospitals. Item Type: Wireless Doorbell Material: ABS Wireless Frequency: 433mHz Ringing Volume: 5 Levels of Volume ( Including Mute ) 0-100dB Transmission Distance: Approx. 200m/656.2ft( In The Open Space ) Button Battery:1 x CR2032 210mAh Button Battery ( Shipped With Built In Battery ) 1 x Button 1 x Doorbell 1 x Doorbell Sticker 1 x Double Sided Adhesive 5 x Screw 3 x Expansion Tube