The use of extensive amounts of lettering and numbering in concrete surfaces has received a substantial boost in recent years as a result of the availability of standard sizes of letters and numbers. Formerly it was necessary for a pattern craftsman to form each individual letter as a pattern for the concrete work and to make a reverse pattern in the case of raised letters. With the standard reversed letters now available in all sizes form 1 /4 inch to 6 inches, legend and dates can be tied in with trademarks and other ornamental inscriptions to achieve almost any desired artistic result. There are three substantial techniques using letter and numbers in precasting inscriptions in concrete. One is the individual letter method. Typically this method involves obtaining standard letters with metal pins on the back. These letters are then driven into the soft pine of the form work. Another is the plaque method. This method involves mounting individual letters on a pattern and casting the pattern in hard brass. This casting is then permanently affixed to a mold and reverses the impression of the letters as well as of the plaque into the mold. Finally there is the changeable inscription method. This technique is used when it is necessary to change the identification in some respects but not in all. For this purpose, several patented devices are on the market which provide for locking individual letters into a plaque and unlocking one or two letters or parts as required.