This cylinder is built to allow a change of combinations by the insertion and operation of the next key in a sequence of 3 keys. Introduction of each new key invalidates the previous key combination.  When all 3 combinations have been used, the cylinder may be reset by a MUL-T-LOCK authorized locksmith.

The product is packaged with the 3 key types, color-coded and clearly marked in a sequence, to guide the customer in correct usage for your locks. First you use the green set of keys that will be provided by our locksmith.
Whenever the combination needs to be changed, simply start using the yellow key (Then the green key will automatically be cancelled). Once again you may change the combination by applying the same process with the red key. (the yellow key as well as the green will automatically be cancelled).  That's right without having to call a locksmith!!