What Our Gearhead(R) Experts Are Saying:"I carried this pack through a fast hut-to-hut stretch, and the waterproof body was a game changer. The AEROFIT system keeps the load close without trapping heat, and the roll-top lets me adjust volume on the fly."Multi-day mountain missions demand a pack that keeps weight low while staying steady over rugged terrain, and the Syclon XP 40L Backpack is built for exactly that rhythm. Its waterproof, fully taped main compartment protects layers and sleep systems when storms move in, and the roll-top closure expands or compresses as our kit changes from dawn starts to late-day descents. The AEROFIT(TM) carry system hugs close without feeling restrictive, allowing air to move freely across the back on long climbs and warm traverses. A front stash pocket stores the layers we cycle through most, while flat side pockets hold 1L bottles where they're easy to grab mid-stride. Base and side compression straps stabilize the load in technical sections, and the walking-pole attachments keep hands free for scrambling. Hipbelt pockets offer quick access to fuel or essentials, and the rear hydration sleeve separates water storage from the main compartment for easier organization. Designed for big mileage and variable weather, it keeps our gear protected and our movement smooth.