SUPER EASY TO INSTALL - Ready to work right out of the wireless doorbell box. Plug the doorbell receiver into a socket and fix the doorbell mitter on anywhere you want with the included accessories(bottom plate,double-sided adhesive tape and screws). WEATHERPROOF MITTER - The mitter is rated IP55 weatherproof and acceptable for outdoor use. The wireless range from the mitter to the indoor receiver is up to 1000 feet(300m),it adopts advanced wireless mission technology(FSK+FHSS) to avoid the wireless signal interference from other wireless devices and can go through /walls/floors/and et SMART&COMPACT RECEIVER - The doorbell receiver has 35 optional melodies and 5 adjustable volume levels(includes Mute mode). Expandable up to 32 mitters and unlimited receivers for complete coverage of your property and match different melody with different mitters to differentiate which one is being detected(Such as the melody for the front door is "Doorbell Chime",and for the backyard is "Dog Barks") MEMORY FUNCTION - Remember your last settings for the doorbell unit ( such as the different melodies for different mitters) even if the AC power goes out. No need to reset the unit, it is super convenient to use and it is also a good ideal for any occasion such as house,apartment Colour:Black Material:plastic Package Contents: 1 x Wireless Doorbell 1 x Chime Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.