Recommendations for Choosing Combinations for the Master 4 Digit Resetable Combination Padlock (Model 175 and Its Family)

As noted on the previous page, the lock can be physically compromised. For light security applications where the lock is suitable, we provide these guidelines:

a) Preferably, choose a random 4 digit number for your combination, and commit the combination to memory. However, if you decide to choose a combination that is easier to remember, do the following: Avoid numbers from 1900-1999, since many people use their birth years or a parent's birth years as combinations, and a thief will try the 100 combinations corresponding to years. Avoid other easy to guess numbers, such as 1234, 4321, 2222, etc. Also avoid famous years such as 1492, 1776 or 1812. Avoid using numbers from your phone number or your favorite pizza parlor's number, your street address, etc. that someone can look up. Avoid using your ATM or credit card PIN number, especially for a health club locker. If a thief gets your combination (possibly by physically compromising the lock,) he or she can come back later, open your locker, take your ATM or credit card and use your locker combination as the PIN. Furthermore, a crafty thief may replace your lock with his or her lock, programmed with your combination, so you won't know anything is wrong, thus giving the thief more time to run up charges before you know your ATM or credit card is missing.

b) Always reset the dials to 0000 (or some other specific number) immediately after you open the lock. Otherwise, someone can get your combination just by looking at the thumbwheels on an open lock.

c) To generate a random combination by hand, shuffle a standard deck of cards. Draw a card. If the card is a face card, set it aside and draw cards until you don't get a face card. The number on the card is your first digit, where ace is 1 and 10 is 0. Put that card back (but not the face cards) and reshuffle. Draw a card for your second digit and reshuffle. Repeat for digit 3 and 4. Verify that the combination generated is not something that is easy to guess. If it is, start over.

d) To generate a reconstructable combination based on something easy to remember, we suggest selecting a four letter or longer word, such as CLOUD. Now, find the positions of the first four letters of the word in the alphabet. For CLOUD, C is letter 3, L is letter 12, O is letter 15 and U is letter 21. Drop the tens digits, and you have 3251. Dial 3251 on your lock. Now draw cards from a shuffled standard card deck, until you get an ace or a numbered card less than 10. Turn each of the four thumbwheels forward the number of positions corresponding to the card drawn (ace = 1.) Thus, if 8 were drawn, you have 1039. This becomes your combination. Set 1039 into the lock, using the manufacturers instructions. If you forget your combination but recall your code word, regenerate the combination for your code word and dial it into your lock. Now, advance all four thumbwheels one position. Try to open the lock. If it doesn't open, advance all four thumbwheels one position again. Within 9 tries, the lock will open.

If you have lost the combination change tool and want to change the combination, click here for instructions.

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