Short Circuit Tester for USB ports.
Protect your expensive USB devices by first plugging in the PassMark USB S.O.S. device to detect bad ports that would otherwise do damage.
The PassMark USB S.O.S. device itself is nearly indestructible for the purposes of testing USB ports with protection of up to +-100V.
The big “PASS” sign is illuminated in green when all voltages are within specification.