We took our wish-list for a minimalist hard shell and ticked it–waterproof-breathable, check. Ultralight (4.8 ounces for a medium), check. Taped seams, check. Storm flap and adjustable hood, check. The Isotope begs for long alpine routes, quick-and-light trail runs, or a mountain bike jaunt when the weather looks iffy. It's so light, so compressible, you can stuff it in a jersey pocket, or it practically gets lost in a hydration pack. Our favorite back-up shell for everything under the sun (and wind, and rain…).