How deep is deep enough? When itâs time to start exploring the back of the backcountry, trust the guide-grade Burton [ak] 31L Pack to perform just as well on the climb as it does on the descent. Completely redesigned to maximize efficiency in the backcountry, multiple zipper options let you organize and quickly access safety tools and gear. The updated horizontal board carry system re-ups fit and security, while refined shoulder straps make this proven pack an even lighter load to carry. Proven and developed in some of snowboardingâs most inhospitable environments by professional mountain guides and team riders like Jeremy Jones and Jussi Oksanen, this pack conquers when other packs crumble.