Simplified Dialing Procedure for Models 2002 and 2010

These locks can be opened by dialing the two number "reverse" combination, as follows: Turn the dial
left two turns and stop 7 marks before reaching the first number in the factory combination. Now right a full turn and then stop 3 marks before reaching the second number in the factory combination. (On some locks, this is exactly one turn.) Now left until the dial stops. Pull the shackle to open the lock.


1) The first and second numbers on one of our locks are 15 and 25. We turned left two turns, then stopped at 8 (7 marks before 15.) Then right one turn and continued to 28 (3 marks before 25). Then left until the dial stopped, and pulled the shackle to open the lock.

2) The first and second numbers on our other lock are 5 and 35. We turned left 2 turns and stopped at 38, 7 marks before 5 on the dial. Next, we turned right exactly one turn. We were at 38, 3 marks before 35, so we didn't turn any further. Then we turned left until the dial stopped, and pulled the shackle to open the lock.

Design Change to Thwart Our Method of Opening Models 2002 and 2010

Because this lock is sold as a "high security" lock, it should be difficult to open it by manipulation as well as by force.

Our method of opening this lock could be effectively thwarted by adding one cam to the lock design. This change could be made to new locks coming off the production line, but would likely not be practical as a retrofit for existing locks. The user would still dial a three number combination, but would need to turn the dial one extra turn between numbers: 3 full turns right and stop at the first number, 2 full turns left, then stop at the second number, 1 full turn right and then stop at the third number, then left until the dial stops. Pull the shackle to open the lock. (We understand that there are combination padlocks used in high security applications, but not readily available in retail stores, that require 3 full turns before dialing the first number.)

It would still be possible to open the lock by manipulation. However, the process would take a lot longer, possibly hours instead of minutes, effectively thwarting our method.

However, we don't know if adding the cam would compromise the security of the lock in other ways. If so, users would be required to do extra dialing with no improvement in security. Some ways that the security might be broken:

1) The obvious: Observing the user open the lock. If the dialing sequence is more complex, the user may take longer to dial, giving an observer more opportunity to view the numbers. Just observing the first number being dialed would narrow down the number of combinations to try by a factor of 20 or 40.

2) A computer driven motorized Locracker might still get the lock open in minutes. (However, the lock won't catch on the right combination if the dial is turned too fast, limiting the speed of a lock cracking machine.)

3) It might also be possible to find the combination using ultrasound or X-ray technology to examine inside the lock.

Where to Buy These Locks

These locks are not widely in stock in stores that carry other Master locks, although those stores may be willing to special order. However, these locks are readily available on the internet. The best price we found was $7.50 each plus tax and shipping for model 2002. (Some web sites offered better prices, but required that the buyer place an order for a large quantity of locks.)