The fastest way to reduce your tent''s weight is to leave it behind altogether. Enter the South Col Bivy, for years a top choice among mountaineers for its durability, value and light weight; it comes in an eVENT fabric (a lightweight laminate) version that is even lighter and packs down to almost half the size. A dual-direction waterproof zip further reduces weight and makes getting in and out easy, while a wire-supported brim keeps the fabric off your face.

A bivy bag seems like it should be a simple thing to cook up. Sew a zipper and a few yards of waterproof fabric and, voila, "bivy sack extraordinaire." However, if you''ve ever toughed out a grim night with damp fabric plastered against your face and snow blowing up your nose, you''ll know it''s not that simple. The Integral Designs South Col bivy sack ($235 for regular length, $245 for long; 20 ounces) is proof positive that performance-minded design and fabric choice are the keys to a peaceful night''s sleep. The South Col''s hood featured a generous rain flap, as well as a light malleable internal wire that kept the fabric from lying against my face, allowed for custom bending to accommodate my sleeping position or ventilation needs, and packed easily. The waterproof 22-inch torso zipper provided easy access and made venting a breeze, while the double pulls on the shoulder-to-shoulder zip were easily adjusted.

For the South Col''s skin, Integral Designs uses eVent''s expanded Polytetrafluoroethelene (ePTFE) laminate fabric. eVent allows vapor to transpire through the fabric rather than having to condense into liquid to pass through the fabric''s pores, avoiding the clamminess we''ve all come to know and dread. I''ve used an eVent jacket-and-pants setup for the past year, and still marvel at the fabric''s breathability; it''s not surprising then, that it shines for bivy-bag use, allowing for excellent breathability while maintaining waterproofness. The bag''s bathtub floor is a sturdy coated nylon, just in case you find yourself sleeping atop a puddle.

Unless you opt to torpedo down a mountain while ensconced in your South Col, rest assured that the bag will deliver years of solid performance for all those "planned" nights out.

"This Canadian manufacturer has specialized in shelters for climbers since they were founded in the eighties. The tops of all of their sacks are made from Tegraltex, a waterproof breathable material, and the floors are polyurethane coated. The models that they make that are most suitable for climbers are the South Col and the Salathe. Both have eye level openings on the hood, which are ideal for ledges where you have to sit up. The zipper admits the rope. The South Col has a removable hood stiffener and no-see-um netting. The Salathe has zips on both sides and three sliders on each, so that you can use both arms while remaining in the bag."

"This sack has a TegralTex upper (a waterproof/breathable fabric that worked on par with Gore-Tex), and a coated nylon floor. The South Col solves the material-in-your-face problem with a thin flexible wire that is sewn across the head. The wire keeps the head of the sack propped up, yet stuffs easier than the Bibler Hoop. The opening goes shoulder to shoulder and sues a double slider. Another zipper extends down the side of the bivy to the thigh, letting you flop the whole thing open to vent, weather permitting. Another nice touch: Integral Designs makes both Right and Left zips, so you can mate it to the zipper on your sleeping bag. The South Col has zippered, non-removable mosquito netting. This was one of the heavier sacks in the test (probably due to all the zippers), yet because it vents so well, is on of the least claustrophobic sacks. It is also an affordable $200. Ron, Steph, and I picked the South Col Bivy over all others."

Summary:
The Endurance Bag Cover is ideally suited for tarp camping in wet and stormy conditions. Paired with a lightweight poncho such as the SilPoncho (also from Integral Designs), the bivy-poncho/tarp combination can provide an incredibly light and versatile raingear-shelter combination for the backpacker skilled in tarp camping.

Final Grade B+ We found the bag cover to be a very good design, but we would have appreciated a floor that was waterproof under high pressure and the option (perhaps in another version) of a more storm-proof hood design.

Full Review

Integral Designs hails out of Calgary, Alberta. Their bivy bags are designed to keep out what my wife, a native Albertan, describes as Alberta''s serious weather. If the high price of the Bibler Tripod is too expensive, then the Unishelter is a practical, affordable alternative, without sacrificing performance.

The mesh panel on the Unishelter is the largest of any of the bivys tested. The fly can be unzipped all the way to the waist, allowing lots of moisture to escape on warmer nights. On wet nights, leaving the zipper open enough to allow ventilation allowed some water to drip onto the mesh. I don''t imagine this would be much of a problem unless you are camping in an environment with heavy rain and wind. The single hoop pole at the head requires a stake to stay upright, and provides ample headroom without the weight of a second pole. I found it very easy to get into the Unishelter. The tall hoop at the head and slightly-longer-than-half zipper made it one of the easiest bivys to get in.

The Unishelter has a basin style bottom that surprisingly accommodated my extra wide Therm-A-RestTM with no problem. The fly is made with Integral Designs own waterproof breathable fabric, TegralTexTM. Weighing 2 lb. 6. oz., the Unishelter adds a little to your pack, but it''s 5" x 18" package fits easily into an overnight pack. The Unishelter retails for $235 online. Summary: The Unishelter is an excellent bivy for 3-season protection. The reasonable price and competitive weight make it a good option for ultralight trips.