Wool has unique properties and is well suited as a base layer because the material is very breathable as well as it keeps you warm if you become wet. Another thing that makes wool base layers amazing is their temperature-regulating properties that will keep you warm on cold days, while it can help cool you down on hot days. Just like technical gym wear, wool will dry quickly compared to e.g. underwear in cotton. Wool also has a microclimate in which bacteria do not thrive. This means that wool will smell less - even when you get all nice and sweaty. Often it’s enough to air dry it after use instead of washing it. That’s good for both you and the environment.