Heavy-Duty Combination Door Chain & Dead Bolt Lock Set Heavy-duty security - both door chain and dead bolt in easy-to-install set; includes hardware Solid 1/4" steel dead bolt, high-strength barrier against opening, tougher than handle-type locks 3mm steel chain with welded links to prevent stretching or bending, 7" length Chain allows partial opening to identify visitors, receive packages while maintaining security Heavy-gauge steel, galvanized for superior corrosion resistance; all mounting hardware included