The Pro-Series 4 Piece Set Adjustable Scaffolding Outriggers attach to the Pro-Series 6 Foot Multi Use Scaffolding Unit to keep the unit stable when double and triple stacked. Adjustable width from 23 to 26 inches allowing the scaffold to be safely stacked. Ideal for home improvement projects like painting, patching drywall or cleaning windows. Meets all OSHA and ANSI scaffolding regulations.