49-356 B123 x structure number would need to be cut for a control key, for a factory master keyed system. This is why a structure number would be required. You can also order a cut key (48-401 B123) cut to a control bitting, but you would have to specify the control bitting when ordering and the key will NOT be stamped "Control". 35-401 B123 would be a key blank for both (operating and control). You would have to Key the Master with 49-356 to get it as a control cut key. Then 35-401 would be used for a control blank key.
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