AVANTEK Wireless Door Bell, CB-21 Mini Waterproof Wireless Doorbell Operating at Over 1000 Feet, 2 Remote Buttons Can Have Different Tones, 52 Melodies, CD Quality Sound and LED Flash

This wireless doorbell has two bells that can be placed outside and a remote that can be programmed to produce 50 different sounds, including tones, melodies and noises like a dog barking. It is easy to set up and allows the user to have different tones on each bell, which helps identify which door the caller is at. It costs less than $20 and has been reported to work perfectly in houses with two different entry points. The sound is loud enough to be heard throughout several rooms but not annoyingly so. It has been used in a 1,000 sq ft cottage, a 1,500 sq ft office, and a two-story house as caregiver notification. It is not known if four transmitters can be paired to one receiver. The transmitters are not illuminated.