No battery required, press with your finger to generate electricity, the transmitter has a built-in kinetic generation module, and press the doorbell to convert the mechanical energy into electrical energy to generate a wireless signal. Rainproof and dustproof function, improved vertical structure design rainproof, wind and rain do not affect the use. A dual-use is not only a doorbell, but can also be used as a pager, a pager for the elderly, a pager for pregnant women and a baby pager to protect your family when you sleep soundly at night. Long-distance transmission has strong penetrating power, 150 meters long-distance transmission in an open area and 30 meters long-distance transmission in a room. Innovative research and development of energy harvesting generators, after 200,000 continuous press tests to a long product life. Receiver size: 78x54x20mm Transmitter size: 66x40x20mm Color: As shown Material: ABS Plug type: EU plug, it is applicable to Indonesia, Germany, France, Spain, Italy and so on. Voltage: AC220V Package contents: 2 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 allowed measurement error is +/- 1-3 cm.