1. Oil tempered torsion springs designed for 50,000 life cycles. 2. Solid aluminum rods – 5/16" or 3/16". 3. Durable links (standard 1/8" thick, or heavy duty 3/16" thick). 4. Cylinder locks concealed in the bottom bar. 5. Choice of two grille patterns: -Standard up to 30' wide -Heavy duty for all sizes 6. Heavy duty extruded aluminum guides and bottom bar.
