| All 25 individual CD's for use on your computer, installed on a USB flash drive. Works on almost all computers with a USB port. Most files are Adobe PDF, so you can store these on your computer or laptop, or print out individual articles. Over 1000 different articles on old locks, safes, new locks, strange locks, plus reprints of all sorts of manuals. 1930's lock manuals, key machine manuals, and so much more. This is a must have reference for the locksmith.