<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Road King:
I guess I must be a little slow as I still don't understand what good these do if they are cut off after you've checked you luggage. 
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The point to having these is:
(a) you have a lock, but you risk it being cut off. you don't want to lose your lock
(b) you don't lock your bag but it is never opened by TSA so it never gets a plastic seal. then your bag is shipped without a lock.
(c) with a disposable "lock" it discourages tampering because the bag is not flagrantly left unprotected, but in case the bag is flagged by the chocolate detector, you don't mind it being removed since the thing is single-use anyway.