Quick Link™ Exit Port and QL HydroLock™ Bite Valve Adapter: tube clicks off for faster refilling with auto shut-off New Fillport: industry’s largest opening with air-light ¼ turn open/close for quick, secure seal that can’t be over-tightened; lighter weight lower profile design Low-profile, baffled design reduces reservoir stack and maximizes stability QL HydroLock™ offers easy, one-handed on/off water flow on drink tube Quick Link™ and QL HydroLock™ drink tube: quickly and easily attach any CPC accessory including the USMC standard filterInsulated drink tube cover protects tube from harmful UV rays and abrasion CamelBak® Got Your Bak™ Guarantee: If we build it, we'll Bak it™ with our lifetime guarantee