The MSR E-Bivy is a lightweight shelter designed for campers and hikers who need a compact, breathable layer between themselves and the elements. It’s essentially a weather-resistant sack that slips over your sleeping bag, helping keep you dry and protected from wind and ground moisture.

Made with a nylon inner lining for comfort and a silicone-coated nylon top, the E-Bivy sheds light rain and wind while letting excess moisture escape. Its floor is built from 15D polyurethaan ripstop nylon treated with Xtreme Shield and a Durable Water Repellent (DWR) finish, which adds abrasion resistance where you need it most. At just 170 grams and packing down to 18 x 10 x 10 cm, it tucks neatly into your pack without weighing you down, and at 224 cm long by up to 91 cm wide it accommodates most sleepers.

The 15D ripstop nylon refers to the fabric’s “denier,” a measure of thread thickness—15D is very fine, keeping weight low while ripstop reinforcement prevents rips from spreading. The DWR finish causes water to bead up and roll off rather than soaking in, and the Xtreme Shield polyurethane coating adds a moderate waterproof barrier (around 1 200 mm hydrostatic head), enough to handle light to moderate rain.