Envelopes/mailers are a common self-sealing package used to ship small/thin items such as bundles of paper, clothes, etc.
They come in multiple styles such as bubble, stay flat, and poly mailers, depending on the level of protection or outside color desired.
Mailing tubes are used for longer products that are small in diameter. These tubes are either circular or triangular. The dimensions of the tube are measured by diameters, by length of usable space, or by the thickness of the board desired.
Plugs can be added to each end to secure the contents inside. Tubes are commonly used for long and thin products such as rolled up posters, fishing poles, etc.