what is lump on usb cable
Hello,
Usually this "lump" is a ferrite filter to filter any external or self induced interference, this is sometimes necessary for longer cables to achieve the maximum possible data transfer speed.
These filters are available in a lot of other interface cables: (telephone and netork (RJ-11 and RJ-45), monitor cables, etc.
For the "Not for MAC" I think the cable and physical interface is universal but the device using the USB may have firmware that is not compatible with MAC Operating system.
regards,
GAM