Check the listing for details. Fitbit One Black & Holder -version 6.46 new battery.PLEASE READ THE DESCRIPTION!. Color: Black, Condition: New other (see details). Listed at 48.00 USD. This fully working tracker has a new battery installed but comes with functionality limitations.It was sitting in a box and missed the opportunity to be upgraded to the latest firmware, so now it will remain on the 6.46 version partially supported by the Fitbit app: Mobile Fitbit app (iPhone and Android) - data sync and upgrade are not working even after linking it to the app. The only reason to connect it to the Mobile Fitbit app is to set up/sync time on your tracker.Don't try to update/upgrade it via any app - it will fail, and there is no workaround. What works:It counts steps, distance, floors, and calories. Shows time.The battery holds for more than a week. What doesn't work:Sync data to the Fitbit phone app.Firmware update/upgrade All serial numbers are tracked due to increased eBay return misuse issues. Comes with a new holder/clip.