Will this reservoir fit my camelbak "go be" waist pack (very old)?
Honestly have no idea. I have mine in a small kelty backpack.
Hey, I just measured it, and its about 11.5 inches long (when there is no water inside) and it expands about 4- 4.5 inches thick (when there is water inside). Even though my reservoir is 2 years old, I still use it for backpacking, mountain bike racing, rock climbing, etc. So it's definitely a good purchase.