At 33 liters, the Pro is Mammut's guide-focused avalanche airbag-compatible pack. The "Short" is designed for a woman's frame — the torso measures about 2.5 inches less than the regular and hte shoulder straps are closer together. Note that Mammut's Removable Airbag System is sold separately from this pack. R.A.S. deploys the company's one-piece, square avalanche airbag that's meant to keep you floating towards the top of a slide. R.A.S. is removable so you can use the pack without it for resort riding, or zip it into another pack in Mammut's line.* Main product photo is Black/Imperial.