This comes across as a very nice helmet. Looks and feels great, and seems well made. my head measures 59cm so is on the cusp of two different sizes. The M-L theoretically would fit 59cm but I couldn't get it on my head. The L-XL had plenty of room and while I could get it to fit front to back, there was a good thumb's-width gap side to side meaning the helmet would move around a lot, regardless of how tight I made it. My head isn't an unnatural size or shape, and it's unusual that neither of the sizes would fit me, irrespective of any adjustment. Rated it as 4-star for quality but misses out on 5-star just because the sizing seems to have been badly considered.