7308300000 under HS Code STRUCTURES (EXCLUDING PREFABRICATED BUILDINGS OF HEADING 9406) AND PARTS OF STRUCTURES (FOR EXAMPLE, BRIDGES AND BRIDGE-SECTIONS, LOCK-GATES, TOWERS, LATTICE MASTS, ROOFS, ROOFING FRAME-WORKS, DOORS AND WINDOWS AND THEIR FRAMES AND THRESHOLDS FOR DOORS, SHUTTERS, BALUSTRADES, PILLARS AND COLUMNS), OF IRON OR STEEL; PLATES, RODS, ANGLES, SHAPES, SECTIONS, TUBES AND THE LIKE, PREPARED FOR USE IN STRUCTURES, OF IRON OR STEEL - DOORS, WINDOWS AND THEIR FRAMES AND THRESHOLDS FOR DOORS, 8301600009 under HS Code PADLOCKS AND LOCKS (KEY, COMBINATION OR ELECTRICALLY OPERATED), OF BASE METAL; CLASPS AND FRAMES WITH CLASPS, INCORPORATING LOCKS, OF BASE METAL; KEYS FOR ANY OF THE FOREGOING ARTICLES, OF BASE METAL - PARTS, and 8301700000 under HS Code PADLOCKS AND LOCKS (KEY, COMBINATION OR ELECTRICALLY OPERATED), OF BASE METAL; CLASPS AND FRAMES WITH CLASPS, INCORPORATING LOCKS, OF BASE METAL; KEYS FOR ANY OF THE FOREGOING ARTICLES, OF BASE METAL - KEYS PRESENTED SEPARATELY were the top imported HS Codes by M LOK LLC in 2021.