I received some propellers to try out from DYS and Xperdrone (Hobby Cross). They have various sizes: 3 inch, 4 inch, 5 inch and 6 inch. I ran some thrust test on them comparing to HQ and Gemfan props of the same size, and also see how well they perform in real flights and how crash resistant they are.
Let’s check out the XD Stealth 150 Mini Quad frame from XpertDrone. This is probably the smallest frame I have seen that supports 4″ propellers!