Grills shall be of extruded aluminum construction having concealed screws for fixing. These shall be duly powder coated in the shade approved by TMH/ TSL. The grills shall have horizontal bars at 15/30 deg. inclination and flanges on top and bottom. The grills at the end shall have flange on the side as well as per the site requirement. The size of main extruded section for flanges shall be minimum 15 x 15 mm and the louvers shall be 15 mm deep having thickness of mm in the front and 2.8 mm at the rear.