This system is called 3-4 because it has a patent-pending feature that allows the removal of one of its side panels when working close to a wall. This feature is great, but what's more is the sturdy, safe feeling it provides in the four-sided configuration. To achieve this, the design improves the typical tolerances, mostly by adding square fittings where the guardrail connects to the scaffold. It's also adjustable, for a proper fit every time. Multifunction Scaffold not included.