Prehung door and sidelight units are purchased from Antigua Doors by specifying either rough opening or net unit size. We have prepared a diagram titled, Measurement Diagram to illustrate the applicable measurements when ordering a prehung unit. The charts that follow the diagram list the exact measurements in which your prehung unit will be sized depending on the chosen configuration. Standard sizing is highlighted, with a nominal charge applied when the rough opening or net unit size requires a jamb thicker than 3/4". Rough opening and net unit sizes that require the actual door to be built outside of standard widths will have an additional charge.