Since the last few months of 2014 Ebay seller pfxmrg from Illinois in America has been trying to sell these Thai made fakes. Most of them are nothing like real plates from the countries they are supposed to be from, are complete fantasy plates or are very poor quality reproductions, especially the supposedly Chinese ones.
These are very bad imitations of normal Chinese car plates.
Some with the OB prefix have police written on the back but these are absolutely nothing like genuine Chinese police plates of any age and are badly made copies of normal car plates.
A dealer out to rip-off collectors with cheap, fake, scrap.