Demountable copy

Demountable copy is a form of traffic sign in which mass-produced sheet-metal characters are attached to the sign face through means such as screws, rivets and adhesives.
Because of the ability to remove the preformed metal characters from the sign, demountable-copy signs can be easily altered to change their message by removing unwanted sections of the legend and installing new elements.
Some states formerly applied their demountable characters to non-retroreflective sheeting but phased out the process when the glue used began to leak and damage the signs.