What is the advantage of a wool beanie?
A wool cap has all the excellent qualities of wool, such as keeping you warm when it is cold outside, but also cooler than many other materials when it is warmer outside. In addition, a wool cap keeps you warm even if it gets damp and can be easily freshened up by airing it outdoors for a while. Bad odors are neutralized by the wool material in your wool cap.
Are all wool caps thick?
Wool caps are available from the thinnest beanies in Merino wool mix to coarse knitted substantial warming wool caps. Sometimes it can feel comfortable with a fleece windproof wool cap. Also keep in mind that you can use multiple layers even on your head, so if you use a thin cap on the bottom and a thicker one on top, you'll stay warm, even if it's really cold.