Check out this review from road.cc on the Kask Valegro cycling helmet.
The Kask Valegro is a lightweight and well-ventilated helmet with a fairly low profile, The Valegro was developed in response to Team Sky's request for a lightweight lid with maximum cooling.
It's certainly light, our medium-sized review sample weighing just 206g (Kask claims 180g for a small). You get 37 vents here and they do a really good job of keeping your head cool, internal channeling allowing the air to circulate and helping to prevent the buildup of heat and sweat. This is the Valegro's biggest strength – it's something you really notice – making it a helmet to consider if you find that others leave your head too hot in summer conditions.
Part of the reason for the Valegro's ability to keep you cool is that very little of the helmet actually touches your head. Aside from the fit system, contact is limited to narrow pads (I'm talking about narrow from side to side; they're 5mm deep) that run front to rear, allowing air to flow relatively unhindered.
Kask's Octo Fit adjustment system is excellent, connecting to the rest of the helmet at the temples and the rear. You alter the fit via a clicky wheel, as is usually the case, while the cradle offers a whopping 50mm of up/down movement at the back of your head. The occipital pads –the bits that contact your head back there – are independently adjustable too, so you can allow for any asymmetry. The overall feel when you have everything set up right is of a helmet that surrounds your head rather than being perched on top.
The straps are worth a mention too. For a start, I like the way that Kask constructs them to fit around your ears rather than using plastic dividers like nearly everyone else.
I also like the eco-leather (synthetic leather) chin strap because it looks neat and doesn't dig in like some webbing, lifting the overall quality just a smidge.