A storage
system (20) has substantially-parallel stationary first and second walls (21, 22) spaced from one another. A third wall (29) is mounted for movement relative to the first and second walls. The improvement comprises track means (26) for guiding movement of the third wall relative to the first and second walls. The track means has a first track (31) mounted on the first wall, a second track (32) mounted on the second wall, a
carriage (33) mounted on the third wall and operatively engaging the first track for movement therealong, and a second
carriage (40) mounted on the third wall and operatively engaging the second track for movement therealong. The improvement further includes locking means (28) operatively arranged to releasably hold at least one of the carriages to the associated track for preventing
unintended movement of the third wall relative to the first and second walls. Thus, the third wall may be releasably held in an adjustable position relative to the first and second walls. In the preferred form, there is a fourth adjustable wall (30) that is structurally similar to the third wall.