Fits ours and most other FPV cameras with MTV mount. The 2.8mm is our 'stock' lens and offers a wider view than the 3.6mm lens that used to come with many other FPV cameras. It provides a 87° angle of view compared to 67° for the 3.6mm lens.
Lenses are a personal preference and given their low cost, many pilots keep a few around. The 2.8mm lens is the all around favorite for FPV use.
You'll need to set the focus when you change lenses - just make sure you have access to some goggles or a monitor, set the focus at long distance and lock the lens in place with the locking ring.