The updated M4 pack is perfectly profiled for technical alpinism where climbers use the same pack for the approach and the climb. The removable waist belt padding is comfortable on the approach, then strips down to nothing for technical climbing with a harness. The front panel is constructed from tough 600D Ripstop Polyester for strength and durability and the side panels are constructed from lightweight 100D Mini-Ripstop nylon with a waterproof coating for light weight and compressibility. The exclusive Backdoor system allows access to contents of the pack without having to remove everything on top before gaining access to gear at the bottom. Comfort is assured by the ventilated mesh padding on the back, and breathable, ergonomic shoulder straps with load adjustment systems. The waist belt and chest strap feature the exclusive EZ OP buckles which can be opened with one hand; a feature that is especially useful when wearing gloves. Additional technical features include mesh pockets on the waist and shoulder straps, an external helmet carrying system that hides away when not in use, 2 ice axe carriers designed for use with modern tools, holders for trekking poles, lateral ski holders, and rope carrying straps.