Heard of no.
Seen? Yes.
They are look like 'rebranded' players. Meizu, Onda, Ramos, Gemi....
Looking at the prices though...I'd stick with Brand names, from a reputable store.
Not sure of all of the policies here as yet...So, I dont want to link to a couple of very good ones I know of.
I have a 'few' players, all were purchased from one of them.
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Ramos T8 8GB, Onda vx777 4GB, Onda vx757+ 4GB, Ainol v2000SE 4 GB, Gp2X
