This is just the open water portion of certification, where the student gets to show the instructor their mastery of the skills introduced in the pool. It consists of a MINIMUM of 4 dives but may be more depending on the students performance.
If you're interested public safety diving, scientific diving, or venturing into extremely cold-water, then learning to dive with a full face mask is definitely for you. Because full face masks allow you to breathe from your nose, they are also beneficial for those who have difficulty using standard scuba masks. Diving with a full face mask offers a different experience and that alone may be reason to give it a try. You need to be a PADI Open Water Diver who is at least 12 years old to enroll in the Full Face Mask Diver course.