https://newatlas.com/cesium-133-atomic-wristwatch/31697/
The Cesium 133 atomic wristwatch heads to Kickstarter
May 2, 2015 - The Cesium 133 from Bathys Hawaii is the world's first true atomic wristwatch. Boasting an internal cesium atomic clock that's claimed to be accurate to one...
cesium 133atomicwristwatchheadskickstarter
https://www.hodinkee.com/articles/introducing-the-bathys-cesium-133-atomic-clock-watch
Introducing The Bathys Cesium 133, The First True Atomic Clock Wristwatch - Hodinkee
You're probably seen a so-called
introducing thecesium 133first trueatomic clockbathys