A Full Face Mountain Bike Helmet looks just like a regular dirt bike helmet but weighs less, has lots more ventilation and a wider field of vision. You get way more comprehensive coverage and protection than a standard MB helmet, which covers only the top and back of the head, something sought after by downhill adventure seekers and aggressive trail riders when falls at those high speeds cause greater bodily damage. A Full face mountain bike helmet also protects the face, jaw and chin.