We love to use it as a layer on the mountain, rock it by itself downtown, and even toss it into a pack for our next adventure. When winter hits, we do just about everything in the Rab Microlight Down Jacket. This versatile insulator is filled with recycled 700-fill down that's been given a special hydrophobic treatment to ensure that it dries quickly and retains its loft when we get caught in heavy snows or steady wintry mixes.