Attachment device for securing a shelf to a shelving unit

A shelving unit comprising:

• a plurality of posts each extending between a first post end and a second post end that opposes the first post end;
• a shelf including corner edges that are coupled to the plurality of posts and positioned between the first post end and the second post end;
• and
• a shelf attachment device formed as a separate component from the plurality of posts and the shelf, the shelf attachment device is attachable to one of the plurality of posts, and detachable from the one of the plurality of posts, the shelf attachment device comprising a ledge having a first wall, and a second wall that form an L-shaped support with one of the corner edges removably placed on the L-shaped support of the ledge, the shelf attachment device comprising;
• a collar configured to extend around one of the plurality of posts when the shelf attachment device is attached to one of the plurality of posts, and
• a lock plate configured to slidably engage with the collar to secure the collar to the one of the plurality of posts, the lock plate including the L-shaped support that is configured to receive the one of the corner edges of the shelf.