The simple screw-in design of the Edison replacement nib unit allows the writer to switch points with ease. Simply unscrew the nib from the section with your thumb and forefinger and screw in its replacement. It helps to do this just after a pen has been cleaned to prevent an inky mess. The #6 size nib is a standard size nib that fits in all the Edison production pen models except for the Pearlette and Mina. The nib and feed are included with the housing that screws into the pen section.