ALFATECO GRI model single-leaf drop door. Comprising a vertical-lift mobile door leaf made of a welded galvanised tube structure with customised size and weight. Outer lining made of vertically corrugated plate. Side guiderails with wall-rigged pipes on which the roller bearings slide and which are fitted with an anti-closure system in case the cable breaks. Side counterweight door closing system comprising weight, runner box and cable system with pulleys of suitable size for leaf weight.