I'm kinda with those with the thinking the striped 350's aren't adidas.
No branding on the upper, I swear we saw a shot of the sole a while back that also had no branding?
Beckham and his son Brooklyn were spotted in custom 350xUB's a while back.
Beckham is adidas sponsored for life, so changes are they were custom made by adidas for him.
Rep makers have gone nuts on them though, there are no 'Genuine' ones as such, unless someone has spliced together Genuine...