Twin Zipper Critical Mass packs MB-CMII is shown
Circumference profile 46 / 47 /48 -----------See Pack Volumes - Go Figure! (Click)
The MB-CMII below in various volume stages. click images for blow-ups. Twin zippers are a custom feature for any McHale Pack as an alternative to Panel Zippers. Even in it's shortest configuration in the last photo, the roll-top strap does not interfere much with access to the upper zipper. There is a removeable internal shelf above the lower zipper. This pack is made with Blue Jean HT 420 with over-layed reinforcing of dyed gray full dyneema. Shoulder pads are also full dyneema. Lower row of photos: The pack can still expand 12" taller!