> https://support.apple.com/en-us/HT201700
You can verify that you're using the correct version of the Apple
USB-C Charge Cable with your Mac notebook and its USB-C AC Adapter.
The cable's serial number is printed on its external housing, next
to the words "Designed by Apple in California. Assembled in China."
• If the first three characters of the serial number are C4M or FL4,
the cable is for use with the Apple 29W USB-C Power Adapter.
• If the first three characters of the serial number are DLC or CTC,
the cable is for use with the Apple 61W or 87W USB-C Power Adapter.
• If the cable says "Designed by Apple in California. Assembled in China"
but has no serial number, you might be eligible for a replacement USB-C charge cable.
For a company whose brand was for quite some time "It just works" to ask you to read a serial number, printed in gray, in 4 or 6 point font, off a light gray cable is dumbfounding.Here's a photo of an Apple USB-C charging cable to illustrate what finding the serial number looks like. http://i.imgur.com/ffVLDYl.jpg
The serial number is right below the control key, if you're curious.