Patent ID: 8215526

Claim:
A backpack comprising: a flexible pocket, at least one flexible material shoulder strap connected to the pocket for supporting the backpack on a shoulder of a user, a generally rigid plate and a flexible inflatable bladder in the pocket with the bladder being closer to a back of the user using the backpack than the plate, load bearing means connected to the pocket for holding a load, a tubular extension extending from the bladder and into the shoulder strap for inflating and deflating the bladder, a mouth-inflatable check valve connected to the tubular extension at a location spaced from the bladder and positioned so as to be accessible to the user for inflating the bladder by blowing into the check valve, and a curved semirigid liner inside the material of the shoulder strap near the bladder only for forming a semirigid channel for receiving the tubular extension and allowing passage of air in the tubular extension while preventing the tubular extension from being pinched closed.