What does the little lightning bolt symbol on a USB cable mean?

With so many versions of the universal USB standard released over the past three decades, choosing the right cable can be difficult. The lightning symbol on the connector helps ensure that you select the correct speed and connection capabilities.

SlashGear writes about it.

What does the lightning symbol on USB cables mean?

USB-C has gradually become dominant on both ends of the cable, making life easier for users. However, among high-quality modern cables, there are models with a lightning logo. This indicates that the cable is a Thunderbolt cable compatible with USB-C. The number next to the symbol indicates the standard's generation and maximum speed.

Until 2015, Thunderbolt used the Mini DisplayPort connector. Starting with Thunderbolt 3, however, it switched to USB-C. The current version, Thunderbolt 5, provides 80 Gbps in both directions. In Bandwidth Boost mode, it provides 120 Gbps for sending and 40 Gbps for receiving. The standard also offers 64 Gbps of PCI Express lanes and networking capabilities at the same speed.

The obvious advantage of Thunderbolt 5 for ordinary users is inexpensive, fast memory expansion. For instance, Mac mini owners can add an external SSD with a similar bandwidth to the internal drive, thus avoiding the need for expensive factory upgrades.

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