There are three main types of moped helmets that riders can choose among. The kind that offers the least amount of protection is the half helmet, as it just sits on top of the head without any chin or face coverings. The three quarter helmet covers more, as it comes farther down the back of the head than the half helmet does, while also adding some protection to the sides of the face. The full face helmet, on the other hand, offers the most protection since it also includes a face mask that shields the chin, mouth, and eyes, as well.
Some states require that riders use moped helmets, but not every rider is happy about this law. Therefore, some moped riders wear the bare minimum helmet, which is the half helmet. This type sits on top of the head, and is known for not being very secure in its position, often moving around and even falling off easily in an accident. It does not offer any protection for the face or chin, but it does protect the top of the head. It also allows moped riders to stay within the confines of laws requiring moped helmets without forcing them to cover their entire face if they do not want to.
The three quarter helmet typically protects more than just the top of the head, as it covers the back of it, as well. There is also usually some material around the sides of the face and forehead, but it does not cover the chin or eye area. Not only does this mean that the face is not usually protected in an accident, but also that insects and dirt can get into the eyes and mouth while riding. Of course, these moped helmets can be combined with goggles that protect the eyes, but this still leaves the chin exposed.
Those who want to protect the entire head and face in the case of an accident typically use full face moped helmets, similar to those commonly used with traditional motorcycles. These not only offer protection for the back, top, and sides of the head, but they also usually protect the chin and mouth area. Additionally, there is usually a clear shield for the eyes so that wind, debris, bugs, and rain do not obscure vision or cause discomfort. The shield can typically be flipped up when the rider does not want the whole face to be covered, though of course most riders are best protected when it is flipped down, covering the eyes.