The Nimb is a Smart Ring with a panic button. It can send an alert to a dedicated call center when you press the conceived action button. The alert can be programmed to dispatch first responders, or, to send an alert to a pre-set contacts, such as emergency center, friends and family.
The Nimb ring is not the only Smart Ring in the personal safety segment, but it comes with a unique subscription model and dedicated services such the dispatch center, first responders and so on. Currently this service is only available in the US.