With a removable mouthpiece in the chin bar that increases ventilation and a fully adjustable visor, the MTB 4. 0 Helmet proves to be a full-face helmet packed with unique features. It's comfortable and breathable, and it's ideal for mountain bikers taking on uphill or downhill, trail or e-bike riding. 360 TurbineTechnology reduces both rotation acceleration and impact energy to the head for added safety. A universal sunglasses dock lets us dock our sunglasses under the visor when not in use, and the visor is adjustable for our benefit.