Helmet is really individual item, because you must have 100% compability of shape of your head with inner shape of helmet.
Don't buy this item with prepaid and post delivery, you must try it before paid.
You can find hyper tech helmet for super price but it doesn't fit well for your head.
Most helmets that I tried in shop was tight for my head, only Salomon Bigade is fit well and comfy for me.
And IMHO most helmets of all brands are small-fit, for example my head is 57-58cm, but for comfortable using I need to buy 59.5-60.5 cm helmet.