Here's what other sites are saying:
The lightest and most breathable jacket that Norrona makes, the Bitihorn Aero100 Men's Jacket is ideal for backpacking, hiking, climbing, and even bikingpretty much any activity where the wind'll be blowing and you're likely to be sweating. With a long back for protection from dirt and water, the Bitihorn weighs just 3. 5 ounces and stuffs into its own pocket, too, so you'll hardly notice it on your back or in your pack.
- Backcountry.com refers to the men's version