Weighing in at one pound, the Rab Men's Xiom Jacket is surprisingly lightweight considering all the features that help keep you dry on alpine adventures. A 3 layer Pertex Shield membrane gives this jacket waterproof protection that remains highly breathable to keep you moving up the mountain comfortably. Features like fully taped seams and YKK Aquaguard zippers over the pockets, vents, and front opening help prevent a single raindrop from entering the jacket. A regular fit leaves room for layers on winter expeditions, but the jacket is still snug enough that you won't notice much bulk in warmer weather. The Xiom also features underarm vents to let in some fresh air when you work up a sweat, a helmet compatible hood with a wired peak that stays out of sight while you're belaying, hook and loop cuffs that close cold drafts out of your sleeves, and a drawcord at the hem to keep the jacket snug around your hips so it doesn't rise over your harness. The zippered A line pockets are always accessible even with a backpack or harness on.