Avantek DB-21 review: A wireless, plug-and-play doorbell, no frills included

Broken doorbell? If you can do without video or smart home integration, Avantek has super-affordable—and much simpler—alternative: A battery-powered doorbell that gives you a quick and easy way to take any visitor-notification system wireless. The DB-21 kit—Avantek has dozens of products in this space—consists of three components. The doorbell receiver is a slim, black box, 3.5 inches