The top rear vents are also covered with titanium.  The vents have a mesh opening and are always open -- they cannot be closed.  A channel inside the helmet, molded into the foam liner, directs air from the front vent, down on to the rider's head and out the back.

That's the theory; in practice, however, the vents flow a decent amount of air, but not as much as the best helmets for air flow, the Shoei X-11 and the OGK FF-4, in our opinion.