Comes From PSADNA 

 One of Ebays Preferred Authenticators

PSADNA COA # 

When you see a listing of an autographed item represented as having been authenticated by PSA/DNA, you can verify .whether the item matches the item PSA/DNA actually authenticated by entering the item's unique certification number (quoted above). This number can be found on the item's PSA/DNA Certificate of Authenticity as well as the tamper-evident label affixed to the item itself. You will be presented with the item's authentication date, description, location and a photo of the item