The Black Diamond Twilight Bivy is ultralight at only 10.7 ounces, and is rated for 4-season use.

NanoShield Fabric is both weather resistant and breathable. Packs down to just 3x5 inches.

Specifications:
Capacity: 1 person
Weight: 10.7 oz
Area: 18.5 sq. ft.
Dimension: 82 x 33 in.
Poles: 0
Doors: 1
Canopy: NanoShield
Floor: SilNylon

NanoShield Fabric: Superlight tent canopies and bivys are constructed entirely from NanoShield – Black Diamond’s new proprietary breathable single-layer fabric. NanoShield is extremely water resistant: it has the highest water column rating of any breathable single-layer, single-wall fabric at 1700 mm. Such an outstanding rating is the result of our exclusive Silicone Nanocell coating. This coating has a much lower volume than typical water-resistant coating, allowing the fabric to remain superlight, soft and package. Despite its thin profile, Silicone Nanocell is highly durable with impressive tear strength, making it perfect for high winds and abrasion resistance when guying-out to nearby rocks, ice or trees. It loses nothing in breathability to less-weatherproof fabrics, boasting a Moisture Vapor Transmission Rate (MVTR) of 4300.