Despite what many people may think, tamper-proof locks do not exist.
A bike lock is there to make stealing the bike more complicated, to delay the thief and therefore act as a deterrent.
A good lock has an anti-picking lock mechanism and is made out of materials that require very specific tools to break or cut through, making theft more difficult.
The security rating helps you choose the lock that is most suited to your use. For this reason, B'Twin defined a test protocol with an independent laboratory, CNPP, based on real-life theft techniques.
This unique protocol allows each lock to be given a comparable rating from 0 to 10 indicating how theft resistant it is.