Are USB C to USB A adapters 'reversible'

Reversible or not, that is the question, but not the way you think. The adapter shown came with my Sandisk Extreme Portable SSD.

Why does it have these notches? Can I use it with other peripherals?
Crucial has a similar adapter for their portable SSDs, with similar but different notches. Usually any 3rd party adapter don’t have this. Does anybody know why?

I have one of those SanDisk adapters as well. I found it does not work with a random USB-C cable end so I suspect SanDisk has some sort of “polarity” on their included cable. Please note, I have not done any engineering analysis of their cable.

I feel it important to highlight the recent catastrophic issues SanDisk external SSDs have experienced. Having read a number of articles on this, it appears to be on devices manufactured since November 2022, but that could change over time. SanDisk was mostly silent on this, released a firmware update that did NOT fix the problem, and instead seemed to focus on slashing prices to move units quickly. Ethics at Western Digital seem to have once again become an inconvenience.

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To be honest, I’ve long ago stopped expecting ethical behavior from most companies, especially tech companies. It’s become a race to the bottom for “how much can we get away with?” Apple is one of a handful of companies that I still think it’s reasonable to expect to usually do the right thing.

As for the original question…

Those tabs look to me like they’re designed specifically to prevent “normal” USB-C plugs from fitting there, and to force specially fitted plugs to fit in only one direction—is that what you mean by “reversible”? I’m not sure I’d even trust an adapter or cable that was so far out of USB-C spec as to require the plug to go in only one way; that sort of defeats part of the purpose of the design of the USB-C connector, and signals a lack of care about standards that’s worrisome.

Whether this matters for functionality if you were to, say, cut off the tabs, is an open question, but decent A-to-C adapters are cheap enough right now that I wouldn’t consider it worth bothering with.


Completely agree with you.

I would strongly advise against cutting off those tabs. You can use other USB-A to -C cables with SanDisk SSDs. Just keep that adapter for use only with the SanDisk cable it came with. WD/SanDisk was definitely doing something “different” with that adapter.

I cannot recall at the moment if I ever tried the SanDisk cable on another brand’s device.

The projections do fit into notches on the USB-C cable included with Sandis SSDs (I have 2 Extreme, not Extreme Pro SSDs). However, I could put one over the end of a generic (Amazon Basics(?)) USB-C cable, and the projection overrode the housing, with the cable snapping into the adapter. I then connected the USB-A end to a charger and the USB-C end to my iPhone 15 Pro. The phone began charging.

Sorry my bad choice of word, but yes, I can’t insert it the other way (into a Sandisk cable) and not at all in a non-SanDisk connector. But how deep does it need to go in anyway to work?

Some years ago a Google engineer found numerous USB-C cables to be not compliant.

Is that still an issue?

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Of course it’s still an issue. As long as there are products, there will be companies selling cheap knock-offs that may or may not be suitable replacements. It doesn’t matter what the product is.

I like to think that certification standards and corresponding branding can help determine the quality of a cable, but I also know that it isn’t a perfect solution. For example, with HDMI (which has a pretty strict testing/licensing/branding program), I’ve seen certified cables that fail tests and I’ve seen non-certified cables that pass tests. So branding and certification should be considered an important consideration, but not a deal maker/breaker.

I agree with what you say, but whilst a non-certified HDMI may not deliver what it should, a badly constructed USB-C cable can burn your charger or other devices.

A badly constructed cable of any kind can cause damage.

I don’t recommend shorting 5v to the data lines on your HDMI cable. It could easily damage a TV or the video source. Sure, devices should have protection circuitry, but I could say the same about USB devices.

I think there’s your answer. I have a USB-C cable going from a OWC Raid assembly to my iMac. Early on, the connector simply fell out of the outlet on the iMac side, causing a temporary scramble as data transfer was in process.

Later on OWC started offering a relatively complicated retainer to keep the cable plugged in.

Unlike the Lightning plug and jack, which seem to grip each other quite firmly, that lozenge-shaped reversible USB-C plug can be relatively easily to work out of its socket.

So, the usual speculation on my part, but I think those projections are part of a retaining mechanism.

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