Emprex USB 2.0 External Drive - Manual (Page 11)

7
About This Drive
This DVD±R/RW Writer is also a RPC2 DVD-ROM drive and according
to DVD-Forum, PC chip must be designed into DVD-ROM drives to
record how many times a user has changed the region code. The first
region code will depend on the DVD title you play and you are allowed
to modify the region code 5 times (including the initial one). After the
fifth alteration, the region code will be locked and only those DVD titles
of the same region code could be played afterwards, so set the code
carefully.