An apparatus is disclosed for engaging and releasing a plurality of items. The apparatus comprises a frame having a longitudinally extending support member and at least one group of engagement unit. Each engagement unit has at least one engagement member, and each engagement unit is adapted for engaging, and disengaging from at least one item. Each of the engagement units in the one group is mounted in series for longitudinal movement on the longitudinal support member, and each one of the plurality of engagement units is interconnected to at least one other of the plurality of engagement units. A movement apparatus is provided for engaging at least one but not all of the plurality of engagement units in the one group to displace the group longitudinally on the longitudinal support member.