Features:

38 ringtones to choose from and 3-step volume control (0~85dB).

Eye-catching backlight flashes when someone pushes the doorbell. Particularly suitable for the elderly, deaf, and children.

Uses machine-learning to prevent interference from other wireless transmitters.

Designed to last up to 25 years.

Specifications:

Working frequency: 433 MHz

Receiving distance: 300M(in open area)

Transmitter size: 75 x 51 x 20 mm

Receiver size: 95 x 65 x 24 mm

Receivers Rated voltage : AC 110V-220V -240V

The transmitter 12V23A battery factory pre-installed (battery not included)

Package Included:

1 Black transmitter and 1 Black receiver

Detail Pictures: