4 1/4″ high x 6″ wide x 1 1/4″ deep. Iron and brass construction. Weight: 20lbs. The way this lock operates is once you lock the lock with the key then you dial a 3 letter combination on the combo dial. Once the combination is set, you can then pull the combination dial out of the lock about 1/4 inch. Then you can turn the dial and it will slide an armored plate across the inside of the keyhole preventing the lock from being picked or opened even with the key.