This helmet runs very small! I have a 54 cm head, which should be within the measurements of a small, but this helmet was uncomfortably tight. I returned this and got a different type (Smith Holt) in a small and it fit so much better. Sad because this is a very good quality helmet, I would recommend ordering up a size!Best Deal on a quality helmet around. I could not believe how well this fits and how light it is. All the bells and whistles of the Vantage at less than 1/2 the price. The boa dial on the back works perfectly to get it snug each time when I switch from with a beanie to without. Vents are real nice but you will need to remove your gloves to open or close themAlso as a side note the CooTree C220 sport heads phones fit perfectly as a bluetooth audio option. Much less expensive option compared to OR or Skullcandy. You just have to learn the buttons and adjust the volume with your phone.I ordered the medium based being squarely in the middle of that size by their sizing chart. I couldn't hardly get it on my head it was so tight. But, I understand that everyone has a different head shape, and that plays into it. A large fit fine.It's a good product, with good features, but pretty overpriced for plastic and foam.Seems well made, has many nice features and looks great. My head is on the small size for a 6' 2" male. I bought a med and it fits fairly tight, although the instructions say the helmet should be snug without excess movement. I wore it for hours skiing and didn't get any headache or pain so I guess I got it right. The day warmed up nicely so I opened the external air vents and let some fresh air in, nice feature.Perfect fit, only have used on the slopes 4 times but once you get everything adjusted for your head it stays and no more fiddling with it. Ear flaps are comfy, plenty of room with still keeping my ears warm. Top vent is a bit stiff but stays where you put it.Only advice would be to double check you head size.First smith product, keep up this quality and I'll be back for moreDeliver in 2 days, vendor was prompt and sent a follow up email. Extremely pleasedLight weight and sturdy - even better than expected. However, two minor complaints: The removable ear covers remain in place just fine when skiing. However, every time I put the helmet into my bag they snap out and I need to reinsert them when I put the helmet on. Also, the ear covers become a little uncomfortable by the end of a long day. Minor annoyances on an otherwise fine helmet.Good helmet at a good price, but the one I received (from another seller under this listing) was not a MIPS helmet. Still a good value, but if this is a concern, you may want to verify with the seller first.After trying on seven different helmets this one fit me the best with my goggles and had the features I was looking for. This is a great helmet. It's comfortable, lightweight, and warm. It has some really nice features like the adjustable venting, easy to use goggle strap, and the dial for adjusting the fit is really smooth and easy to turn.Smith products are always of good quality and look the business.This helmet is no exception. Solidly built, comfortable, and looks the business.I bought a large and it just fits a 61 cm circumference head.Size guides I found had L as up to 63 cm for Smith, but for this one at least, I think any bigger than 61 is going to feel a bit tight.Comfortable