CamelBak ThermoBak 3 Liter Hydration Pack - One of CamelBak's most trusted and well known minimalist packs, the ThermoBak 3L continues to impress with updated features and technology. The new 3L, 100oz Mil Spec Crux Reservoir delivers 25% more water per sip while the style maintains the ergonomics and optimal infrared reflectivity it's famous for.