LUCKARM Wireless Door Chime/Doorbell.

Feature Specification
Type Wireless digital door chime/doorbell
Receiver Battery-powered indoor chime
Transmitter Wireless push-button
Melodies About 20–38 selectable tunes, depending on model
Wireless range Approximately 80–200 m in open space, model dependent
Receiver batteries Typically AA batteries
Button battery Typically 12V A23/23A
Material ABS plastic
Frequency Commonly 315/433 MHz, depending on model
Installation Wall/door mounting; no connecting wires
Applications Homes, gates, offices, shops