It squeezes down fine, it has 3 straps on each side.
It takes a large bear canister vertical with lots of room above.
This is HMG's description of the fabric:
CF Nylon Hybrid:
Used as the primary HMG pack material, this fabric is a unique rip-stop Cuben Fiber/Polyester hybrid. Only slightly heavier than our other Cuben fiber versions, this high-performance, rip-stop material can withstand over twice the weight and strain as Cuben fiber alone, and is 100% waterproof.