/lib/udev/rules.d/50-mustang.rules is in mustang-plug 1.1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="1ed8", ATTRS{idProduct}=="0004", GROUP="plugdev"
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="1ed8", ATTRS{idProduct}=="0005", GROUP="plugdev"
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="1ed8", ATTRS{idProduct}=="0006", GROUP="plugdev"
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="1ed8", ATTRS{idProduct}=="0007", GROUP="plugdev"
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