From what i understand from info and what's in the stash is the US made are unstamped and the hole in the middle is central and the stamped ones are the japanese made Hi-Caliber seatclamps with the hole being more off-center, thicker at the back than the front. There are some robbing b*stards on US ebay lately selling cheap ones from Ginni's claiming them as orignal unstamped. I bought 2, (them purple and pink ones doing the rounds) POS, loads of differences, just tat, sent them back for a refund and they've supposingly gone missing in the post, $65 down. Ooh, I'm cross
BTW, your's looks original to me.
