Platypus GravityWorks Replacement Reservoir, 4-Liter Unique, dual-layer laminate combines a rugged exterior with a food-grade, taste-free interior Reservoirs are interchangeable with any GravityWorks system, allowing you to create the capacity you need for any trip 4.0L Kit includes: 4.0L Dirty Reservoir with Quick Disconnect and 4.0L Clean Reservoir