the combination or key alone will no longer suffice). This is why a professional safe-technician will use manipulation rather than brute force to open a safe so they do not risk releasing the relocker. Radiological methods Penetrating radiation such as X-ray radiation can be used to reveal the internal angular relationship of the wheels gates to the flys mechanism to deduce the combination. Some modern safe locks are made of lightweight materials such as nylon to inhibit this technique, since most safe exteriors are made of much denser metals. The Chubb Manifoil Mk4 combination lock contains a lead shield surrounding part of the lock to defeat such attempts to read its wheels. Tunneling into bank vaults Large bank vaults which are often located underground have been compromised by safe-crackers who have tunneled in using digging equipment. This method of safe-cracking has been countered by building patrol-passages around the underground vaults. These patrol-passages allow early detection of any attempts to tunnel into a vault. Safe bouncing A number of inexpensive safes sold to households for under $100 use mechanical locking mechanisms that are vulnerable to bouncing. Many cheap safes use a magnetic locking pin to prevent lateral movement of an internal locking bolt, and use a solenoid to move the pin when the correct code is entered. This pin can also be moved by the impact of the safe being dropped or struck while on its side, which allows the safe to be opened. One security researcher taught his three-year-old son how to open most consumer gun safes. More expensive safes use a gear mechanism that is less susceptible to mechanical attacks. Magnet risk Low-end home and hotel safes often utilize a solenoid as the locking device and can often be opened using a powerful rare-earth magnet. Electronic methods Electronic locks are not vulnerable to traditional manipulation techniques (except for brute-force entry). These locks are often compromised through power analysis attacks. Several tools exist that can automatically retrieve or reset the combination of an electronic lock; notably, the Little Black Box and Phoenix. Tools like these are often connected to wires in the lock that can be accessed without causing damage to the lock or container. Nearly all high-end, consumer-grade electronic locks are vulnerable to some form of electronic attack. TEMPEST The combinations for some electronic locks can be retrieved by examining electromagnetic emissions coming from the lock. Because of this,