Steel and Aluminum non-vision transfer grills allow air circulation with a sightproff grille area. No- vision and no- vision no- light (darkroom) grilles are constructed from steel or aluminum inverted v-blades that allow maximum air distribution in a non vision package and are used in doors and partitions for ventilation of non ducted areas. Our U.L. rated fuseable link grilles can satisfy those job requirements where a fire rated door assembly needs ventilation.