TrackR

TrackR is a commercial key finder which assists in the tracking of lost belongings and devices. Trackr is produced by the company Phone Halo and was inspired by the founders' losing their keys on a beach during a surfing trip.
The founders of Phone Halo began working on TrackR in 2009. In 2010, they founded the company and launched the product. 
In Winter 2018, TrackR rebranded itself to Adero, as part of changing its focus to other uses for its tracking technology, taking TrackR beyond the Bluetooth fobs that had been the core of its service.
Overview.
The device contains a lithium battery that needs to be changed about once a year by the user. It communicates its current location via Bluetooth 4.0, to an Android 4.4+ or iOS 8.0+ mobile device on which the TrackR app is installed and running. This feature is referred to as "Crowd Locate", since each device will report its location to all other TrackR devices in range, including those that are neither owned nor registered by the user. This feature is useful, because the app must be installed and running on a nearby Bluetooth enabled device for any device's location to be relayed.
As of August 2017, over 5 million TrackR devices had been sold.
Technical data.
For "Trackr Bravo", the producer published following data as of August 2017: