Horizontal Wind-Bar Reinforced PVC Industrial High Speed Door For Wide Span Warehouse Openings Reinforced Industrial High Speed Door For Wide Span Openings Wide and large-span openings are the hardest working doorways to keep stable. A broad PVC curtain has more surface area to catch air, so without reinforcement it tends to flap, sag, and billow, which hurts performance and reliability. This Industrial High Speed Door is designed around one core selling point: reinforced PVC