The idea is simple. Just put the combination lock to the USB connector and the data inside the USB have been protected physically.
But in my opinion, it is not as secure as you might think because I was successfully cracked a combination lock by bruteforcing it. It just took about 20 minutes to turn the combination and unlocked my uncle’s briefcase. Don’t think me wrong. My uncle forgot his briefcase combination and I helped him to recover it. Seriously, it is easy to unlock but takes a lot of time to bruteforce.