Earlier quoted context omitted.
I don't buy the pen testing part. I might as well sell a hammer and call it a pen testing device. Funny enough they have the following on their website: "A hammer used maliciously can permanently damage to a third party's device. The USB Killer, used maliciously, can permanently damage a third party's device." Contrary to this device a hammer can be used a useful tool too.
It's designed to prove a point. To prove that USB devices can be malicious. It's probably most useful as an education tool, training staff not to plug random USB devices they find lying around the parking lot into their computers.
Might make sense, yeah. How many computers would get blown up during such a test, and how much productivity would be lost and how much money would it cost? What is the expected cost of a major breach or malware infection? How much less likely does a breach or malware infection become as a result of leaving one of these laying around? I actually wouldn't be surprised if leaving these did come out positive, in much the same way that regular fire drills come out positive.