The crisp, clear, colorful display is very user-friendly

With a built-in orientation sensor, the FNB58 automatically adjusts the display to accommodate the device's orientation. The tester features an intuitive rocker switch and a back button for straightforward navigation. 

The buttons are kept to a minimum

But this simplicity hides a lot of power, and I suggest downloading and getting real familiar with the user manual, because there's a lot to this gadget and it's easy to find yourself facing some scary-looking warnings.

Beware the scary warnings!

One feature of the FNB58 that I really like is the real-time voltage and current waveform screen that gives me an at-a-glance idea of what the meter is sensing, which can dramatically speed up a diagnosis. For intermittent faults, the meter can log up to 9 hours of waveform data.

The waveform display functionality is awesome

Another useful feature is the ability to read E-mark chip data found in higher-quality USB-C cables. This chip allows the cable to communicate with the devices it connects to, providing information about the cable's capabilities, power capacity, and supported features.

Reading the capability of USB-C cables from the E-mark chip

The Fnirsi FNB58 is a powerful, versatile, and, at just over$50, affordable USB test meter. Not only does it give you the usual volts/amps power information, but can see this information as a waveform, and even do multi-hour data logging. It can read E-mark and DASH cable data, carry out cable resistance tests (this can uncover internal cable damage that is otherwise invisible), display what charge protocols are being used, and much more.

Also: How to unlock the Flipper Zero's true power

That's quite a list of features, and it's far from complete.

The display is one of the best I've seen on a USB meter, and the user interface is simple. But there's a lot more to this meter, and I recommend reading, re-reading, and then reading again the manual, and spending time experimenting with the meter to get used to what it can do and what to expect from it. 

If you want a cheap meter, theKJ-KayJI 2 in 1 USB tester is a good, sub-$25 option, but if you want more functionality and capability, theFnirsi FNB58 is a huge step up for little more than double the money.

See also

• This$30 gadget claims to add years to your phone's lifespan. Here's how
• This is the USB flash drive James Bond would use
• How to strip wires like a pro (and my must-have tools)
• Stop! Your Apple charger may be a counterfeit, and this tiny gadget can tell
• This$10 gadget is my favorite repair tool of all time