The metallic curtain is made of insulated steel blades in galvanized steel Z 275 of 18-gauge (1.31mm) embedded into each other. The height of every blade is 3’’. The extremities stoppers on each alternative blade are made of malleable cast iron and allows engagement and locking of the curtain in its place in the guide rails. The bottom bar is an extruded aluminium profile and comprises a U-shaped Santoprene weather-stripping rated for extreme cold. Finally, the bottom blade is made of two angles 38mm x 38mm x 3mm at minimum.