Nick Green wrote a review of Giro Xen Helmet on September 15, 2011
Great helmet overall. Very comfortable, snug, customizable fit thanks to the strap in the back. Doesn't move around while biking, and has good ventilation. Also fits well with my GoPro helmet strap. Only con is that the rear strap for customizing the size doesn't stay put very well and is easily expanded on accident. This is normally not a problem though as once it gets on your head, it stays put very well.