The hood is small and fits relatively close to the head. It would be quite uncomfortable over a helmet. The hood doesn’t have any adjustments so this small fit keeps it snug. It is also lined to block the wind which helps it slide over hair and hats well.
The L4 is the warmest synthetic non-belay jacket I’ve worn, yet it is still quite low profile. It isn’t very puffy at all. The insulation is packed a bit denser than it is on The North Face’s standard Thermoball jacket, and that pays off in the warmth department.
Being a bit heavier and low profile gives the jacket a good feel. It’s warm right when you put it on as opposed to a high-fill down that takes a few minutes to warm up. It has a distinctly less technical feel than high-performance down, while still fulfilling the high-performance requirements. Sure, it’s a bit heavier than the equivalent down, but it still packs down super small, it will keep you warm soaking wet, it has five pockets, and you don’t have to baby it because the shell fabric is pretty robust, unlike a lot of high-performance down.
As far as warmth goes, I haven’t gotten the L4 into any extremely cold conditions, but I feel comfortable down to the mid 20’s in the city with just a T-shirt beneath it, or throwing it on over a fleece mid layer at the top of a windy peak in the mid-to-low teens. Much colder than that and I might be wearing a few other layers anyway, so the L4 would likely still get packed.
I’ve been waiting for a long time for someone to knock a mid weight insulator out of the park, and if the cuffs were a bit shorter, the L4 would be in the Rock Pile. (For those who don’t live in Colorado, that would be a home run.) As it is, the L4 still flies deep into the outfield. The combination of a killer fit and a perfect level of insulation makes this jacket my Go-To for most of my cold weather activities. On top of that, it also looks good enough to wear in the city.