CamelBak Mil Spec Crux 2.5L Accessory Reservoir, Features:

• Purpose-built reservoir so you can stay hydrated and hunt longer
• 25% more water per sip so you stay better hydrated
• Quick Link Hydrolock: Easy one-handed on/off water flow with Quick Link modularity
• Hydroguard Technology
• Insulated Tube Cover: Maintains water temperature and protects the tube