The key to the Altras carrying comfort is the C2 back system, a low profile suspension sheet keeps the centre of gravity close to your back & transfers the weight efficiently onto the hips. Its simple, uncluttered & highly efficient. Combine this with the fully adjustable Gridlock shoulder straps & the Load Transfer Disc hip belt & you have the ultimate carrying system. Gridlock means that you can completely remove & independently adjust the straps horizontally & vertically to get a completely customised fit. Load Transfer Disc lets the padded hip belt pivot as you walk allowing unrestricted movement & ultra efficient load transfer. The hip belt can also be completely removed for travel security & cleaning. The Altra has a pear shape design which helps to keep the pack load low & close to your back minimising load movement & backward pull for ultra efficient carrying. A high density polyethylene foam back panel provides comfort & support, aided by twin aluminium M stays for structural integrity. Shoulder straps use Hypercell foam, an open structure polyurethane foam that provides structure & comfort. All the fabrics on the Altra are rip stop nylon with higher density weaves on abrasion areas. All the fabric is silicone coated to repel water & dirt & then backed with PU for additional protection & strength. One of the best features of the Altra is the Wingman hip pockets, angled perfectly to allow easy access whilst carrying the pack they will accommodate 1 litre water bottles & anything else you need instant access to. An external kangaroo pocket, basically a large bellow front pocket with zipped access & a top compression strap, will swallow extra kit & then compress down when not required. Access to the main compartment can be either through the top lid or via the ingenious U Zip. It acts as quick access on either side, or by unclipping the bottom flap; you can completely unzip the whole bag to get massive access to all your kit. Poles can be attached using the compression straps & ice axes are easily stored & removed using the Pax one handed axe attachment system. Basically you can remove an ice axe without taking off the pack by simply reaching round & drawing the axe downwards to release it.