This is a 3″ builder upgrade colonial casing with a built-ing backband. It comes in primed Finjer Jointed Pine 15′ lengths. You would not need a backband with this one. Casing is used to trim around doors and windows. It covers the gap between the drywall and the jamb. Casing is often the most prominent trim feature in your home and should be thicker than the baseboard. To increase the width and depth of the casing you can add a back band.