A USB ‘Condom’

Protect all your devices by putting this in all your USB connections.
Protect all your devices by putting this device into all your USB connections.

Say, what?  A USB condom?

Alas, yes, that’s what the world seems to be coming to.  In colloquial language, when engaged in ‘unsafe computer connections’ over a USB port, a USB condom might be just what the ‘doctor’ ordered and save you from an unexpected computer virus infection.

So what exactly is a USB condom?  Nope, no rubber involved, neither any unrolling.

It is instead a simple small device, little more than an inch in length and the same general cross-section dimensions as a USB connector, that connects between a USB cable and a USB connector.  It is sometimes more formally described as a ‘stop synch’ or ‘charging only’ connector.

It is used when you are wanting to simply charge a device and not connect up or do any data swapping between the two devices being connected – the one providing power and the one seeking power.

How it Works and Why

A USB connection has four wires – two wires for power and two wires for data.  If you are only wanting to charge something, you don’t need the two data wires, indeed, you don’t even want them.  The data connection can be obscurely dangerous, because increasingly, hackers are finding ways to worm into your devices (mobile phones, tablets, etc) via an ‘unprotected’ USB connection between a device they are already controlling and your device.  This type of connection can also potentially bypass much of the firewall and anti-virus protection on your computer, making it particularly insidious.

Note the danger can exist in unexpected ways.  For example, your friend’s computer might get infected, he then uses its USB connection to charge up his phone, and the infection travels through the connection to his phone.  The next day, he is at your place and asks if he can top up his phone battery, and connects to your computer, allowing the virus in his phone to now travel down the USB connection and into your computer.

In other words, you are at risk not only when connecting your device to some other power source to charge from, but also when connecting someone else’s equipment to your equipment.  You might think you are ‘only’ allowing the other device to charge up from your power source, but unbeknownst to you, there might be a malicious program in the other device lurking and waiting to travel down the connection, even while no obvious programs are active at either end of the connection.

It is entirely possible to be infected with, eg, a PC virus, but from some other sort of device such as a phone or whatever else.  So don’t think that just because you are connecting a tablet and a laptop there is no chance of infection.  Any type of connection can allow for viruses to pass.

There are also stories of seemingly safe public power charging stations, such as you sometimes see in airports and convention centers, being maliciously developed and having secret data capabilities to infect devices connected to them.  We have no personal knowledge of such things, and don’t know how real the danger may be; on the other hand, we’ve never had our credit card ‘skimmed’ at an ATM but accept the reality of that risk, so perhaps there is a small but appreciable risk when using what seems to be a simple charging station anywhere.

Fortunately, the solution is simple.  Just put one of these devices inbetween any devices and the USB power sources the devices wish to connect to.  Even more fortunately, the cost of such devices is very low.  Amazon sell them at a price of $12 for two.  They are pretty much universally compatible with all devices and connections.

A Bonus Feature

These units have a bonus feature too.  They will sometimes set the connection between the unit supplying power and the unit requesting power to allow for faster than standard 0.5 amp charging.

Modern devices can sometimes accept charging at rates of up to 2.5 amps, and some won’t even charge at all when only receiving the standard 0.5 amps of power.  Some tablets use power so rapidly that if you connect them to a 0.5 amp charger they are using up the power faster than it is coming down the line, and so they don’t charge at all (just discharge more slowly).

Sometimes these little units will work to increase the rate of charging that occurs, and sometimes not.  We’ve not completely sure why or when (and have a suspicion that using our lovely USB tester influences the results), and so, view it as a bonus if it happens, rather than an essential feature.


This small device connects inline between devices and other devices when using a USB connection.  It prevents any data exchange between the two devices, protecting you from any unwanted transmission of viruses.  It takes up little space and almost no weight, and costs under $10 on Amazon.  Recommended.

1 thought on “A USB ‘Condom’”

  1. Use a small portable battery when going out for more than 10 hours. No possible problems. You have recommended some in the past. I do not need another devise to tote around. And extremely rare that I would ever plug into someone else’s laptop. But everyone has different circumstances.

Leave a Reply

Scroll to Top
Scroll to Top

Free Weekly Emailed Newsletter

Usually weekly, since 2001, we publish a roundup of travel and travel related technology developments, and often a feature article too.

You’ll stay up to date with the latest and greatest (and cautioned about the worst) developments.  You’ll get information to help you choose and become a better informed traveler and consumer, how to best use new technologies, and at times, will learn of things that might entertain, amuse, annoy or even outrage you.

We’re very politically incorrect and love to point out the unrebutted hypocrisies and unfairnesses out there.

This is all entirely free (but you’re welcome to voluntarily contribute!), and should you wish to, easy to cancel.

We’re not about to spam you any which way and as you can see, we don’t ask for any information except your email address and how often you want to receive our newsletters.

Newsletter Signup - Welcome!

Thanks for choosing to receive our newsletters.  We hope you’ll enjoy them and become a long-term reader, and maybe on occasion, add comments and thoughts of your own to the newsletters and articles we publish.

We’ll send you a confirmation email some time in the next few days to confirm your email address, and when you reply to that, you’ll then be on the list.

All the very best for now, and welcome to the growing “Travel Insider family”.