This is the second such pump I have owned - the first died, after several months of use it would not hold a charge and would not turn on. While I like the light weight of the device and the accuracy of the output, I found that there were issues. First off, the display is very difficult to read (even in a darkened room) and it was on both devices I've owned so it wasn't a coincidence, it was the same on both. On the 2nd unit I bought a power supply cord which broke right at the end where it connects to the pump. Although I liked the pump and the price, I don't see myself being able to buy a third one.