1.Long distance transmission provides you with a better experience 2.Install and use without wiring 3.Long distance transmission with strong penetration power 4.Waterproof design 5.The sound is loud and adjustable in four gears Volume level: Four adjustable levels (can be ) Music selection: 36 (default Dingdong Dingdong) Emitter: With indicator light, press the button and the light will turn on Emitter: One 12V 23A battery Receiver: With indicator light, rings and the light is on Receiver: Using 3 AAA batteries, without battery Scope of work: 300M straight-line on open ground (data sourced from factory laboratory) Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use Colour:Black Material:abs Package Contents: 1 x Doorbell sticker 1 x Double-sided tape 2 x Screws 1 x Transmitter 1 x Receiver 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.