This family of products continues to delicately balance the characteristics that define reliable ultra-light apparel. For example, the U.L. Down Jacket weighs less than most cotton T-shirts, blocks a deceptive amount of wind, 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.Ballistic Airlight Nylon Made from 15-denier Ballistic nylon, Ballistic Airlight nylon is an ultra-light and ultra-thin fabric. Because of its tight, durable weave, Ballistic Airlight has high wind resistance performance and it feels silky soft.Ballistic nylon is one and a half times more abrasion resistant than other similar weight fabrics and boasts three times the tear strength of nylons that are almost 20% heavier. Because of this, Ballistic nylons have allowed us to reduce the weight of many of our products by more than 50% without sacrificing the durability. We create Ballistic nylons by heating and stretching nylon fibers. Much like Tensiled steel, this process aligns the nylon molecules in each fiber, dramatically improving the strength and stamina of the fabric.Polkatex® DWR Treatment Unlike other water-repellent fabrics, Polkatex will retain its ability to keep you dry wear after wear, wash after wash. Here"s how it works: Polkatex is treated with a water-based fluorine finish that adheres to the fibers of the fabric, providing excellent water resistance. Polkatex also contains a cushioning agent that "fills in" the molecular bonds, giving them a unique elasticity. This elasticity allows the bonds to rebound from the excess wear and tear that can result from harsh detergents and oils. Water-repellent and abrasion resistant, Polkatex lasts.