The diminutive, ultralight and weather-resistant MSR E-Bivy sack can be tossed into a pack lid on any trip, providing essential protection for an unplanned night in the hills, or added warmth and comfort when used under tarps or on open bivies. Its silicone-coated fabric top blocks wind, dew, spindrift and precipitation, making it the perfect emergency shelter. Weight: 0.18 kg