The thickness and width of most profiles can be cut to different thicknesses and/or widths other than STANDARD however the profiled portion does not change. In the sample profile below the thickness could be set to custom 1" and the width could be set to custom 6" however the profiled section on the 6" moulding will remain 2 13/16. Customizing gives you the flexibility to use a profile like this as a casing eg. (4" x 1") and a baseboard eg.(6" x 7/8)".
NOTE: Casing back checking is standard on all profiles