I always get requests for U.S. Surplus. Well, this is one product I personally love and believe in. These are the infamous 1 Quart plastic canteens that have been in service from the early 1960s until the present day. Most of these have an NBC cover, but the cap for the opening will probably be missing, as well as the plastic piece that connects the cap to the canteen (always found those annoying anyway).
These are all used heavily, but still in totally functional condition. Covers are the same story, but all are inspected to have both ALICE clips and functional snaps. Although these have been used, they are built so tough that they have PLENTY of service life left in them.