Feature: 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. Specification: Item Type: Wireless Doorbell Material: ABS Plug: US Plug AC100-240V 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 ). Package List: 1 x Button1 x Doorbell1 x Doorbell Sticker1 x Double Sided Adhesive5 x Screw3 x Expansion Tube