Wireless Doorbell with Waterproof Memory Function, No Battery Required, EU Plug, Smart Home Night Light - 4 Modes: Sound only, flash only, sound and flash, sound and light on. Light on mode can function as a night light - Memory function: Remembers the previously set melody after power is turned off, no need to reset - Self-powered doorbell, no battery required. Ensures reliable operation without worrying about battery life - Features bright LED lights and loud ringtones, ideal for elderly individuals and pregnant women - Self-powered button uses kinetic energy technology, no battery needed Specifications: - Receiving distance: Up to 150 meters in open area - Volume: Adjustable up to 100 dB, 58 selectable ringtones - Rated voltage: AC 110240V, 5060Hz - Working frequency: 433MHz - Receiver standby power: < 0.5W - Receiver dimensions: 86 x 78mm - Button dimensions: 80 x 41mm Package Included: - Option 1: 1 x Receiver, 1 x Transmitter - Option 2: 2 x Receivers, 1 x Transmitter - Option 3: 1 x Receiver, 2 x Transmitters - Option 4: 2 x Receivers, 2 x Transmitters