Ideal for active hunts in the warm, early-season woods, these hydration systems feature a collapsible plastic bladder that fits into the pack. An attached tube runs up the shoulder strap. The sipping spout can be clipped close to your jaw, so you can take a drink by simply turning your head. Still-hunters and drive hunters don't have to stop and create extra noise and movement to take a drink. Also, because the weight is centered across your back, it's less bulky than carrying a water bottle on your hip.