I feel my E5336Bs-2&Bs-6 getting hot after long hours usage. Is there safety concern?

Like most other electronic devices, E5336Bs-2&Bs-6 get hotter during charge or big data transfer. It is a quite normal phenomenon if working in regular office environment. Even if it worked in hot environment, E5336Bs-2&Bs-6 will automatically power off if its temperature reach 60℃for safety protection. (Please don’t use E5336Bs-2&Bs-6 in close environment; it will cause poor signal and high heat of your E5336Bs-2&Bs-6).