regarding you zy1270, I see that there are also some zy1271 and zy1273 floating around?, what is the newest of all these?
There's actually a ZY1272 too. A brief summary of the new/different features on these models:
ZY1271 - large colour TFT display (same as ZY1270's), features USB type-C input and output ports, plus an micro-USB input port.
ZY1272 - same size as the ZY1266 but with a colour TFT display, automatically stops charging/discharging beyond a set current threshold
to prolong battery life.
ZY1273 - same size as the ZY1266 but with a colour TFT display, supports USB 3.0 and an input USB type-C port (but no micro-USB port).