Ring's smart lock has a hand crank so it works even if the power's out

Ring's smart lock has a built-in hand crank to generate power when the batteries are dead.

Ring's smart lock has a built-in hand crank to generate power when the batteries are dead.<p><img src="https://www.engadget.com/img/gallery/rings-smart-lock-has-a-hand-crank-so-it-works-even-if-the-powers-out/intro-1791369915.jpg" /></p>