Sonic Adventure 1 watch. It is official. Though it is plain, it has an engraved back from ewatchfactory.com. The engraving has the Sega/Sonic logo, copyrights & 2 lines of text (custom) It was a ltd. offer for the release of Sonic Adventure 2 & retailed for $25. You could choose from any of the SA2 main characters, plus a chao & band color.
Yes, it's the same EWatch Factory from above on this page, but this shows they also had either 2 rounds of releases, or selectable art that wasn't shown the first time. The hands placement on this one isn't very good though...they're in his mouth! Info by Blue Sonikku