Correctly used, shields and boxes give a safe space for workers who must enter an excavation. They should be maintained, as they may fail without warning, especially after abuse or misuse, and the manufacturer's instructions on installation, use, removal and maintenance should always be followed. Boxes should not carry loads above their design limits; correct benching and battering lowers earth pressure on them. Storage and transport should follow the manufacturer's instructions, and heavy equipment may need dismantling for transport. Boxes should be inspected regularly for damage and altered or modified only with a competent person's approval.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.