Abstract: A one-piece non-load bearing passive locking member for releasably securing an end panel assembly to a slotted upright. The locking member includes a base part having an aperture extending therethrough. A spring part is formed in a first end edge of the base part for urging the locking member into locking engagement with a slot of the upright, and a locking tab is formed in a second end edge of the base part opposite the first end edge for lockingly engaging with the slot. A hollow guide part extends transversely from the base part and has a cantilevered arm extending transversely within the hollow guide part from a wall of the guide part, and a planar spring compression limiting part extends at least partially over the spring part from the wall of the guide part. A retaining pin extends longitudinally through the hollow guide part and from a free end of the arm in a direction transverse to the base part.