What are the key YI 4K+ Action Camera features? Related articles Where can I find and download the YI Action app?(YI 4K+ Action Camera) Is there a QR code for YI 4K+ Action Camera? What is the Electronic Image Stabilization(EIS) function? How to use it？ What scenes are my camera suited for? (YI 4K Action Camera) How long is the official warranty since the time of purchase ?