The challenge: create the lightest and warmest insulation layer possible, without compromising on fit or features. The result is the highly refined MontBell Ultra-Light Down Inner series. This family of products delicately balances the characteristics that define reliable ultra-light apparel. For example, the U.L. Down Jacket weighs less than most cotton Tee-shirts, blocks an amazing amount of wind, and is warmer than most heavy fleece jackets, while compressing to the size of a 32 ounce water bottle. Specifically designed as a replacement for the heavy and bulky fleece garments used by many backcountry enthusiasts, the U.L. Down Series is what you need when warmth is critical, minimal weight is paramount, and space in your pack is at a premium.