That sounds like inductor whine, though not sure you should be hearing it. Could be faulty or could be that your hearing is sensitive to it. You could refer it to the seller as a fault.

I watched the Klarus Mi7 video linked above and was liking it until the reviewer showed you could turn the switch on without knowing where it is by wrapping your finger around the head and squeezing, gave me the impression it would be susceptible to accidental turn on in a pocket. I don’t have one so it might not be the case but something to watch out for.

Edit:-Sorry the T10 didn’t work out, and even more sorry you’re coming down with the 14500 bug :wink: