Round mailing tubes include mailing tubes that are adjustable, colored, crimped-end (or folded-ends), and telescoping. Round tubes are cylindrical and made with material strong enough to protect documents such as blueprints, posters, or documents. Use round mailing tubes for mailing papers that are too large to fit into an envelope. They are constructed from a strong 3-Ply spiral wound for strength and durability. These tubes sealed with white plastic end caps and are available in 2" to 3" diameters and 6" to 36" lengths.End caps are plastic caps that seal the end of a round tube.