USB C cables can have variations in speed, power, and protocol capabilities.

Additionally there are different length requirements to watch out for. When in doubt, buy cables from the device manufacturer. You can also buy USB C cables from Adafruit as we have specific cables for specific needs that are all tested and researched.

E-Marker Chips Inside Cables

All Type-C cables except the minimal combination of USB 2.0 and only 3 A must contain E-Marker chips that identify the cable and its capabilities via the USB PD protocol. This identification data includes information about product/vendor, cable connectors, USB signalling protocol (2.0, Gen speed rating , Gen 2), passive/active construction, use of V_CONN power, available V_BUS current, latency, RX/TX directionality, SOP controller mode, and hardware/firmware version. It also can include further vendor-defined messages (VDM) that detail support for Alt modes or vendor specific functionality outside of the USB standards.

An interesting video on E-Marker chips: https://www.youtube.com/watch?v=PqR_AkXQp0Q

See the next page for a sample device that can read E-Marker chips.

Speed

A USB C cable with 3.1 Gen 2 capabilities vs one with 2.0 can mean a vast difference in data transfer. For example, two cable types transferring the same HD movie can take vastly different times:

• 3.1 Gen 2 takes 5 seconds at 10 Gbps
• 2.0 takes 1.7 min at 480 MBps

USB C cables run at different speeds measured in bits per second. These include:

• USB 2.0 (2001)
  • 480 Mbps (megabits per second)
• USB 3.0 (2011)
  • 5 Gbps (gigabits per second)
• USB 3.1 Gen 1 (2014)
  • 5 Gbps
• USB 3.1 Gen 2
  • 10 Gbps
  • *Note USB 3.1 gen 4 in store?”
• USB 3.2 (2017)
  • See Wikipedia for a breakdown.
• USB4 (2019)
  • Should not be labeled USB 4.0
  • Based on the Thunderbolt 3 protocol but devices may or may not be Thunderbolt 3 compatible
  • See more on Wikipedia.

If you run across the term “Full-featured” this a reference to speed and typically means USB 3.1 Gen 2.

Going forward, the USB-IF, as of 2025, recommends labeling ports and cables by their speed, rather than the standard they support: