Flat Key Versus Radial or Tubular key

​There are many lock designs in general use; some use flat keys of various types and others use tubular keys. Numerous variants of each are available from different manufacturers. The overall level of security available from each of these types of lock is defined by five main factors.
  1. The number of effective key codes (or "key differs") the lock offers.
  2. The physical strength of the lock, ie. its resistance to outright attacks using tools.
  3. Its resistance to picking or other forms of manipulation.
  4. The ease (or otherwise) with which it is possible to obtain keys, both legitimately and also from unauthorized sources.
  5. Whether you need many of the locks to be keyed alike. Some mechanisms are more easily incorporated into a wide variety of locks, enabling one key to open locks of many types within a set (or "suite").