Vasteko Wireless Doorbell Kits No Battery Required for Both Transmitter and Receiver, IPX7 Waterproof Push Button, 3-Level Volume, 25 Ring Tunes (White) NO BATTERIES AND NO WIRES REQUIRED - Transmitter is used the unique PUSH-RF technology. When the button is pressed, it converts kinetic energy into an electrical signal to ring your wireless doorbells. So no more worrying your push button runs out of batteries and no more hassle in buying awkward weird batteries to run your push button. You will always be able to hear your doorbells ring! IPX7 WATERPROOF TRANSMITTER - The internal components of the transmitter are waterproof coating, you can soak it in the water for long time, it still works well. Receiver is made of ABS plastic, inflaming retarding and environmental protection. DEPENDABLE OPERATING RANGE - Each doorbell is set with a unique radio frequency code at the factory.This gaurantees your doorbell will not interfere with other remotes devices, and its 400ft(120m) operating range means you can place the plug-in unit several rooms away from the door. CHOICE OF 25 CHIMES AND FLASHING LIGHT INDICATOR - This unit lets you choose the best way to be notified when someone is at your door. In addition to your choice of 25 selectable chime tunes, there's also a flashing light indicator that gives you a visual form of notification (an excellent feature for the hearing impaired). 3 levels of adjustable volume from 25db-85db (low- middle-high). Customize your volume easily by volume button. EASY INSTALLATION - Plug-in receiver with 2-Pin US plug is suitable for an electrical outlet (AC); Mount the Push Button Transmitter to the wall with the provided screws/anchors, or stick it to the wall by using the enclosed double-sided adhesive tapes.