Authentic Tiffany & Co. Heart Tag Bracelet. It is an older model without the "Return to" engraving. Both sides are engraved so you will likely want to get it removed and redone, which is common practice. The current engraving is "NFL" on side 1 and "BJG" on side 2.
I wore this for a few years in 2005-2006 before I got divorced and it has sat in my old jewelry box ever since. I recently found it and am ready to sell :-)