Protective cups offer protection for contact sports. They are usually made of hard plastic or steel and perforated for ventilation. A more flexible and comfortable soft cup is also offered for low contact sports such as soccer. A flex cup variation features a hard exterior cup with a soft cup lining.
In Jiu-Jitsu competitions, protective cups are forbidden but many practitioners use them in training.
Check out the effectiveness of a cup when faced with a straight on kick, a metal bar and even an uppercut:
