Never mind enemy gunfire, IEDs, ditches filled with bodily fluids that you have to crawl through or the long, sleepless days; by far the most irritating part about being a solider is having to put your helmet on when it's cold or that 0500hrs reveille which sees you poke your head out from your bouncing bomb to find it's yet again, another baltic day on the plains.
It's no great surprise then that you'll often see people bimbling around with all manner of hats and beanies on underneath their helmet trying to put a protective layer between their fragile bonce and the plastic head guards.
The downside to this is that you risk the fit and comfort of your helmet as the beanie will often push it away from what it's meant to be protecting. All this means that should that piano drop out of the sky, then you've potentially sacrificed your safety for the sake of some warmth (or if you take a 7.62mm and it doesn't do that whole ricochet around the edge thing which I've seen happen to a colleague in Afghan, lucky git).
Thankfully, Armadillo Merino, specialists in all things Merino wool have entered the fray with their Kojak beanie. Never mind that it's named after possibly the coolest lollipop sucking detective in TV history, it's also the proud holder of numerous benefits brought on by the 100% Merino wool construct.
Unlike synthetic materials which when subjected to intense heat or flame has a tendency to melt or worse yet, combust, Merino wool is fire retardant. This is extremely important when you consider some of the injuries sustained by soldiers that have found themselves caught in blasts and there are enough reports out there stating this very fact. This was also the main reason why the wearing of synthetic tops by troops in theatre was banned (Of course, not very heavily enforced).
This in itself is enough to put the product above almost anything else in the market as it's hard to find 100% natural clothing suitable to harsh environments that you'd expect a beanie in Afghan to face for example.
The other strong feature is that it's able to thermally regulate the area it's covering. This means that the heat maintained by the beanie should be a comfortable range just above body temperature, with the wool trapping enough heat whilst simultaneously releasing enough heat to keep a good balance.
All this is good and well, but by far the biggest winning feature is the thickness of the beanie. It's thin; thin enough to fit happily and comfortably under your helmet without adjusting the fit, thin enough to keep you warm but not too warm and thin enough that it doesn't cause any noticeable rubbing or chaffing once the helmets on and you're jogging around like a lunatic.
Some concerns were raised over how the beanie would fare under duress for a long duration - Would the sweat build up? Would it cause chill the second you took the helmet off?
Thankfully, Armadillo Merino have a feature called 'No Chill' which means that if the garment can't wick the sweat away and cause it to evaporate, perhaps because there's body armour on top of it, or in this case a helmet, the moisture is prevented from going back against the skin and as soon as the material is exposed to outside air, the evaporation process begins in earnest.
This is far more pertinent in the use of body armour, but for the helmet, considering how much body heat is lost through the head (Depending on which scientists you listen to), it's an important fact to keep in mind.
Personal experience of the Kojak with tin lid in place confirms all the initial assumptions and proves its worth; for once putting on a cold, even slightly damp helmet doesn't make you think about becoming a Postman instead.
UPDATE: After four years, it's yet again proof that Armadillo are among the very best. The Kojak is still doing its thing and has continued to perform in all manner of terrain. From just out and about on a cold day, to running, to under a ski-helmet in Austria, the Falklands, Kenya, etc, it's held it's own.
It's amazing to see that there's almost no sign of wear or tear - Merino wool is so robust and long lasting that there's no threading, no seams splitting, and it's been fairly ragged around. It's not got the thickness as mentioned above, but even in the coldest of sub-zero temperatures, it keeps you warm. It also, shockingly, still smells fresh, even without a wash. (Genuinely can't remember the last time it was washed... some years ago....).
Well worth the money and you can trust it to look after you.