Not sure why BUT it is my 4th one that has broken and in the same exact place. I do have to say they have replaced everytime for free BUT what a pain. The call. Then the email. Then the proof. Then it happens again in 3-4 months. Customer Service at NATO told me in Dec 2018 that they are having stronger ones manufactured. Lets hope. But again product has been a piece of crap HOWEVER Customer Service has ALWAYS replaced