Sakrete 18-in Tube Form in the Concrete Forms department at Lowes.com
Amazon.com : MagicWater Supply Mailing Tube - 2 in x 18 in - Kraft - 12 Pack - for Shipping and Storage of Posters, Arts, Crafts, and Documents : Office Products
1.5 bore x 18 stroke hydraulic cylinder, welded cross tube double acting cylinder | Magister Hydraulics