The Chinese government has legislation requiring gps units sold in China to have special fw which can 'read' the official maps which have shifted co-ordinates making them unusable on 'foreign' devices brought into the country by tourists or Chinese nationals returning from OS. The 'Venus' non-shifted maps made by syzygy (the freakin' genius!) overcome this restriction by offsetting the official shift, so that standard fw like on your unit can use those maps. If i've any of that got that wrong, i'm sure Caty or syzygy will correct it. Short version: official maps with the shift are useless in your unit, but Venus will work. I hope you understand simplified Chinese anyway.