BLACK KNOBS: Oblate black door knobs crafted with high quality porcelain and finished with a glazed coating. The matte satin nickel finish offers both beauty and durability, making it a perfect choice for various architectural styles ZINC ALLOY ROSE: The interior door knob with sturdy round zinc rose is secure mechanism. And easy installation, saving you time and effort DOOR THICKNESS: Fit most of standard door thickness 1-3/8 to 2-1/6 inch (35-55 mm). Adjustable 2-3/8 or 2-3/4 inch (60-70 mm) backset optional ZINC LATCH: Adjustable 2-3/8 or 2-3/4 inch backset optional. The handle latch is forty five degree turning to open doors, it's convenience for all people QUALITY PROMISE: Ensure opening cycles exceed two hundred and fifty thousand times as ANSI Grade three standard