Osprey Packs Hornet 46 Backpack Side mesh pockets with InsideOutTM compression keep water bottles and other gear secure. An overskirt compression strap provides further compression of internal contents. An external hydration compartment provides room for a hydration reservoir without sacrificing internal pack storage capacity. Gear or clothing that needs to be quickly accessed can be stuffed into the front stretch mesh pocket. Pockets on the harness strap provide convenient access to energy gels or electronic devices.