This tool ended up really hurting my ears and the warning function isn't automatically on… it has to be turned on. This was crazy to me; especially because, wether or not it is actually on (like can warn you that you will touch your ear drum) is unclear. You swipe it left or right and it turns green when it says off and gray when it says on. I tried to be cautious, but it didn't work, and im genuinely unsure if the warning function was on when I was using it even though u thought it was. Seriously don't buy this.