number to allow the fence to fall despite slight deviation, so that for a given safe it may be necessary only to try a subset of the combinations. Such "slops" may allow for a margin of error of plus or minus two digits, which means that trying multiples of five would be sufficient in this case. This drastically reduces the time required to exhaust the number of meaningful combinations. A further reduction in solving time is obtained by trying all possible settings for the last wheel for a given setting of the first wheels before nudging the next-to-last wheel to its next meaningful setting, instead of zeroing the lock each time with a number of turns in one direction. Guessing the combination Safes may be compromised surprisingly often by simply guessing the combination. This results from the fact that manufactured safes often come with a manufacturer-set combination. These combinations (known as try-out combinations) are designed to allow owners initial access to the safes so that they may set their own new combinations. Sources exist which list manufacturers' try-out combinations. Combinations are also unwittingly compromised by the owners of the safes by having the locks set to easy-to-guess combinations such as a birthdate, street address, or driver's license number. Autodialers A number of companies and groups have developed autodialing machines to open safes. Unlike fictional machines that can open any combination in a matter of seconds, such machines are usually specific to a particular type of lock and must cycle through thousands of combinations to open a device. An example of such a device is a project completed by two students from the Massachusetts Institute of Technology, Kyle Vogt and Grant Jordan. Their machine, built to open a Sargent and Greenleaf 8500 lock on a Diebold Safe, found an unknown combination in 21,000 tries. Lockmasters, Inc. markets one autodialing machine [QX3 Combi Autodialer (LKMCOMBI)] that works on a variety of 3 and 4 Wheel combination safe locks. There also exist computer-aided manipulation tools such as Mas Hamilton's SoftDrill (no longer in production). These tools are similar to autodialers, except they make measurements of the internal components of the lock, and deduce the combination in a similar way to that of a human safe technician. Weak-point drilling While some safes are hard to open, some are susceptible to compromise by drilling or other physical methods. Manufacturers publish drill-point diagrams for specific models