I rented this helmet for a recent climb on Mount Rainier. It was very comfortable and easy to adjust the fit. Like the previous poster I too have a large brain and therefore a large skull. This helmet fit very well. The headlamp clips hold very well and there are enough of them to keep the lamp firmly attached. The only problem I had with it was getting the chin strap clipped in. The snap is rather small and was hard for me to align. I would highly recommend this helmet.

I purchased the Elios after I lost my last helmet. I got the green size two and have been greatly pleased so far. I have a large head(brain too I would like to think). I wear about a 7 3/4 to 7 7/8 and the Elios fits like a charm. I am even able to fit a medium to lightweight beanie on with the helmet on. My previous helmet was a Grivel Salamander, and it was a tight fit with a hat on underneath. My one concern with the helmet is the location of the adjustment nob. If you feel the back of your head where the bump is in the lower center, that is around where the adjustment knob fits. I have a slight phobia of falling and hitting the knob straight into the skull. The helmet fits better with the knob a little lower than the back of the helmet, but I have this irrational concern that the location may be a problem. I would strongly recommend this helmet if you have had problems getting helmets to fit due to brain size. For reference my head is pretty narrow, but long if that makes a difference in fitting.