I completely agree with Ranger Doc Cook. Especially that neck gaiter, one of the best things the Army ever issued me.
If you go somewhere overly cold, I found a good combo for head coverings: neck gaiter--pulled up over the nose, over that the old sleeping hood that came with the old sleeping bag (but is not on the parts list

)--velcro that under your chin, it keeps the neck gaiter from slipping down, then the balaklava over that--also pulled up over the nose. This combo also fits well with the Helmet on.
There's also a heavy sleeping hood and booties that come with a 3-part intermediate(?) cold weather sleeping bag system--the one that has the green compression bag--the workers at CIF apparently haven't realized that the hood and booties are part of the inventory...they gave those back to me when I turned the sleeping bag in!