The standard for competitive CrossFit athletes and the fastest way to perform pullups. Click HERE for a demo with explanation.
Safety Tip: If you do not have a quality overhead position, be careful performing high volume reps of this movement. An easy test is to perform Wall Extensions: if you struggle to keep your hands in contact with the wall, you are a prime candidate for scaling this movement.
The same safety issues exist for the standard kipping Pullup as well, the main thing is to be aware of your limitations, work on your mobility and not overdo it while practicing or performing this movement in workouts.