Giro Xar Mountain Helmet 2012
The XAR offers all the features you've come to expect from Giro's top-level trail-riding helmets P.O.V. adjustable visor; In-mold composition with EPS foam and polycarbonate shell; Roll Cage reinforcement but the XAR heralds a new era of performance, comfort and style. At the heart of this helmet you'll find 17 Wind Tunnel vents as well as optimized internal channeling, and the visor is vented to increase airflow. Breathability on the XAR is incredible; there's never been a lid this breathable on dirt.
By far the lightest and best ventilation of any mtb helmet I've ever owned. In fact ive had three of them. Two of them took serious slams during XC races and because of the fit and quality construction I was totally fine. Your noodle is worth it.