Although this book was written in 1946 the content is appropriate to locks today. Several types of locks are talked about as well as a big variety of alternative methods to get the locks open. This book was written by a locksmith and covers deadlock latches, automatic deadlocks, square or deadbolts, jimmy proof locks, opening filing cabinets, opening desks, opening letter boxes, opening windows, unlocking chain door fasteners, unlocking barrel bolts, opening automobiles, ignition locks, sprung locker doors, padlocks, hinge pins, & much more is covered in this 24 page booklet.