Please never stop making these
I don't know what it is, but the Sweet Protection Helmets always fit perfectly right out of the box. BothSki and Bike helmets. And it's not just me, I have a few friends that exclusively ride with SP and we all have different heads. That's probably the main reason why I don't even bother anymore with other brands, they don't come close to this anatomical fit.
Thankfully also the building quality of the SP helmets is second to none. I put this thing through the wringer. Touring in the alps, Canada, Alaska, Andes, Himalaya. I am not gentle with it and took some nasty falls over the years in rocky terrain. The shell is still perfect. The liner broke as I wash it frequently, and SP just sent me a new one. Free of charge. Great service for a premium product.
After initially riding with a Trooper carbon helmet, I found my perfect match with the Grimnir due to its superior venting capability. 99% I ride with the Grimnir, only when it's extremely cold (below -25C) I take the Trooper out, but you could simply wear a thin merino hat on those days too.
It's my 3rd Grimnir now, one I retired due to age (would probably still be good for another decade) and the other two I switch (one is white and one is black). As long as SP makes this helmet, I will never buy anything else.