Premium Kraft Cardboard Mailing Tubes - 3" x 20" - 3" Opening Diameter 20" in Length - Case of 25 Shipping Tubes with White End Caps (3x20) Premium Mailing Tubes are Made of 3 Ply Spiral Wound Chipboard. Quantity: 25 Kraft Mailing Tubes with White End Caps White End Caps (Included) Fits Tight to Protect Your Shipment. Actual Overall Length is 1 Inch Longer to Make Room for the White End Caps. Wall Thickness: 0.070 in