Osprey Packs Viper 13 Hydration Pack Stretch mesh pockets on the side of the pack allows for both organization and accessibility to gear on the outside of the pack Upper side compression straps stabilize the load while lower, cross functional compression straps also serve as external gear carry straps The blinker light attachment found near the base of the front panel of the pack allows for Quick light attachment for high visibility in the dark An elasticized lid lock helmet attachment system provides storage for your helmet