Bagging big, burly summits call for serious protection, and it doesn't get any more serious than the Arc'teryx Alpha SV Bib Pants. The tough, high density weave, nylon main body fabric stands up to ridiculous abuse, and the waterproof, breathable Gore Tex membrane keeps you dry and safe during all of your backcountry explorations.To earn the Arc'teryx SV severe weather moniker, the Alpha SV bib had to be tough. And, of course, this is Arc'teryx, so when we say tough, we mean it. The bib's main body fabric is N80p Gore Tex Pro 3 layer. N80p is a high density nylon weave. The high density construction minimizes the yarns' exposure to abrasion, which reduces damage to filaments to maintain surface integrity. Areas of high abrasion are reinforced with N155p X Gore Tex Pro 3L fabric, which plies together multiple yarns in an Ottoman weave for maximum bulk and ruggedness. A durable micro grid woven backer reduces weight and further resists abrasion. What all that means is years of service, even in the harshest conditions. Finishing it off, you'll find Keprotec instep patches at the cuffs that resist cuts and tears caused by sharp ski edges or even sharper crampons.The Alpha SV Bib is more than tough fabric it's designed to work in perfect harmony with climbing harnesses and backpacks. This means the large bellowed chest pockets are designed out of the way of waist belts and shoulder straps, and the through crotch zip makes nature breaks quicker, easier, and safer by allowing you to leave your harness and bibs in place. The Expedition fit leaves room for layering, which makes it more severe weather friendly than other bibs. Of course, the Alpha SV is equipped with stormproof zippers throughout.