Disadvantages: expensive, and every night, can't measure heart for people with tattoos wrist straight, apply to other mobile is not in addition to the iPhone 5 or more.
Another disadvantage is expensive, requires recharging the battery every night, can not measure the heart rate for someone with a tattoo on the wrist, with the other mobile not the iPhone 5 and up.
The disadvantage is that it is expensive, be charged every night,. Can not measure the heart for people with tattoos on his wrists,. Used with another phone unless the iPhone 5 or above.