For some reason, one of my Fitbit Flex lights was out and I was a little disappointed because I only bought for a month. After I contacted Fitbit via email that night, I received the reply pretty quickly and they decided to send me another one to replace it. Bravos to their customer service. My cousin told me that her Fitbit went out and she had to replace hers when I bought mine. I don’t really know how fragile this little device could be, but my understanding is that since it’s tracking the activity daily on the wrist, it has to be very strong to keep functioning. The fact that I had to replace my Fitbit in a month made me wonder if my new device could endure long enough before I lose the interest.