The MSR E-Bivy is by far MSR s lightest and most compact weather resistant bivy making it ideal for taking with you for unplanned nights on the hills This E-Bivy has been stripped back to keep both the weight and pack size to a minimum and weighing in at just 250g with stuff sack and with a pack size of just this bivy offers a durable shelter for if you should need it while thru hiking This incredibly lightweight bivy top blocks wind dew spindrift and even light precipitation adding valuable warmth and comfort when used under tarps making it an extremely versatile and incredibly useful piece of emergency outdoor gear