Maximum storage or mailing protection, extra strong Plastic end caps seal tubes (included) Rigid tubes resist bending and crushing Outside: 3.28 x 27" (D x L) Material: .125 thick spiral wound fibreboard Mail documents, posters and hard goods safely. Rigid tubes are 3 ply spiral wound. Tube sizes are inside dimensions. Plastic end caps fit tight - Protect your shipment. Plastic end caps included. Outside: 3.28 x 27" (D x L)