A flexible duct made in flame resistant PVC coated polyester fabric and reinforced by steel helix welded between the two layers. Axial compressibility: 8:1. Used in civil and naval conditioning plants, ventilation systems, suction of fumes, vapours, powders, gas. Flame retardant V(TM)-0 according to UL 94 and M2 grade according to NFP 92 503.