By contrast, for the same brand USB data cable, for same length and same specification, the flat wires have bigger current than round wires, as flat wires have less copper, then the resistance is smaller, it leads faster charging and higher discharge. So portable it is better to use flat cable for battery. And round cable is more convenient, but relatively easy to wind, flat cable is not easy to wind, but easy to be damaged. For round cable, it can be with shielding layer, thus the data transmission is more stable and not be easily disturbed. A round data line is more durable than flat data line, but not as easy to use as flat data line. And the flat data line can not be used if the interface has a bit irregularity, and the round cable will not have this problem. But flat data lines transmit faster than round ones.