Rating: 5 / 5
At 232 grams/8.2oz this is the lightest helmet I've seen. Foam helmets such as this are not the most rugged. It would be crushed before it made it to base camp in the Himalaya.
For me, chin strap, headlamp attachment, sizing (fits with or w/o fleece hat) and weight are the best of any helmet I've tried. I did glue some foam pads in to customize fit. At $100 it is pricey.
Aside from light weight, the foam construction makes it better for protection from blunt trauma than from falling rock (which is a mountaineer's first concern).
Fortunately for me I was wearing it when I took a 40 foot whipper on Charlotte Dome last June and decked out on a ledge after the rope absorbed the lion's share of the KNs.
Neither the helmet nor I survived unscathed, but I my cervical vertebrae and brain would have likely been much worse off if I had been wearing a conventional hard shelled climbing helmet with webbing suspension.