Not required., 138 500 725 - 3m Knocking Bar., 138 500 730 - 4m Knocking Bar., 138 500 735 - 5m Knocking Bar., 138 500 740 - 6m Knocking Bar., 138 106 287 - Maximum Height Warning Sign., 138 100 991 - M16 Expanding Bolt (8 required per Height Restrictor)., 138 106 558 - Height Restrictor Catch Post.