The single guardrail holder makes it easy to adjust your guardrails to the situation.
With two rolling towers build against each other it's not recommended to place a standard guardrail frame in the center. Instead of this you can place the single guardrail holders. Trough clicking the (guardrail)braces on the holders you'll have a steady guardrail.
The guardrail holder is provided with rings so the braces can't slide down. Click the braces between the rings on the holder.
The guardrail holder also has a nylon 6 coupling to attach the guardrails safely to the rolling tower.