A stackable storage unit (1 )may be vertically stacked for storage and transportation of storable members.(8) The storage unit comprises at least one pair of rails (10) extending in a first direction and having a contoured surface for supporting a surface area of a generally cylindrical storable member (8). At least two generally vertical walls (30).extend in the first direction on opposing ends of the storage unit. The walls comprise a flat top surface (32) with a plurality of alignment openings (35) therein. A plurality of alignment tongues (34) extending from the bottom of the wall (30) are positioned and configured to engage corresponding alignment openings (35) in an underlying storage unit. A rib structure (50) underlies the rails and connects the walls to the rails. Feet (46) extend below the bottom of the alignment tongues and support the storage unit on a generally flat surface or fit inside the walls of an underlying storage unit.