With the advent of machine manufacturing, craftsmen were able to set manufacturing to exacting specifications. One advantage of this was being able to manufacture complex objects, such as guns, in separate pieces. The benefit of this was realized when manufacturers replaced only the broken parts of the objects that they made rather than replacing or repairing the entire instrument. By setting machine manufacturing guidelines, manufacturers were able to make large quantities of the components of their products and then later assemble the finished product, increasing efficiency greatly. Replaceable parts revolutionized nearly every industry in the industrial age, paving the way for mass production and assembly line manufacture.