When BattlEye mistakenly bans players due to a false positive, they grant this item as part of their apology (along with the unban).
From the item description:
"Unfortunately, due to to a false positive you were accidentally banned by BattlEye. We are very sorry for this big inconvenience and will do our best to prevent something like that from happening again in the future. As a form of compensation, you get this unique item from the game developers." -BattlEye Team
This item is only given to players who've been falsely banned! Please don't try to get this item – if you've been correctly banned for cheating, then you won't be unbanned and won't receive this item.
What if I was unbanned but didn't get the item?
You don't need to contact us to receive this item! This item isn't immediately distributed. Instead, we'll add the item to your inventory once we have a complete list of everyone affected by a false ban wave. Once we send the items out, it can take Steam up to 24 hours to actually add the item to everyone's inventories.
Items can only be added to inventories of players who've played within the past 30 days. If you haven't recently launched the game, it's possible that the item was unable to be added. Steam requires recent playtime as a precaution against game developers using items as an advertisement to every player on the platform. In this case, sorry to say there isn't currently a way to recover the item.