They are probably the most widely used nib by professional calligraphers. They are very "forgiving" and quite enjoyable.
Very similar to Nikko G. This zebra G nib is just slightly more flexible.
This is the perfect nib for someone who is just starting calligraphy for the first time. It's a very strong nib and requires deliberate pressure to create swells, so you really don't need a practised hand.