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 war