PallStar for those who bunk 4k, 4k is used for post processing purposes. it allows for a cleaner 1080p image. but, for Fpv flight, it's almost negligible due to high speed motion.

PallStar Zooming into the image and sharpening it up, it looks like an MPU-6000

PallStar If you look closely, these are using Nyloc nuts. The nylon insert is smaller diameter than the aluminum, so it creates a resistance on the shaft. This resistance is strong enough to hold the nut in place under normal conditions. It will only loosen when there is extreme pressures on the prop.