If you are in the market for a lightweight base layer that can also be worn a la carte, this is the choice. To me, this model is essentially the Zephyr crew, downsized to a lighter weight. The difference between 18.5 micron vs 17.5 micron may not seem like much, but it is. If you have worn and like the Zephyrs in the past and enjoyed their solid and more heavy feel, this one won't work for you.I was sad to find out that the Zephyr family will no longer by made except for something called the sport. It's a sad day when another quality product is discontinued.