Bivy Sack E-BIVY from the MSR is easy to carry for day trips, open-air sleeping and off-campus trips. Simple design helps maintain thermal comfort and protects against moisture. DuraShield fabric with taped seams and high quality waterproof finish is more durable than thermoplastic and keeps you dry. Very lightweight and compact dimensions make the companion bag even on long journeys where you need to save space and grams.