The guardian stacker bracket end rail - square attaches at the ends of the guardian stacker bracket scaffold system. The square shape is designed for applications where the eave of the roof does not overhang the scaffold walking surface. If the eave does overhang the scaffold walking surface, use the #61237 stacker bracket end rail angled.Complete stacker bracket system is composed of: support bracket (#61129), stacker bracket end rail square (#61237), guardrail post (#61133), top clamp (#61144 - #61149 depending on rail size), and toeboard attachment (#61142). See instructions for full details