corresponding substitute front sections 122 c and 124 c thus the kit contains three substitute front sections a first substitute front section 120 c for the hinge side jamb 120 a second substitute front section 122 c for the lock side jamb 122 and a third substitute front section 124 c for the horizontal header 124 the substitute front sections 120 c 122 c 124 c replace the front section 120 a 122 a and 124 a respectively although fig5 shows the substitute front section 120 c having a depth greater than l b the present invention also contemplates the reverse case l c less than l b where the original frame 110 in its opened orientation has a thickness t greater than the thickness t of the wall opening preferably the substitute front sections 120 c 122 c 124 c contain the same interlock mechanism described above for the front sections 120 a 122 a and 124 a including protrusions 302 and grooves 308 to allow the substitute front sections 120 c 122 c 124 c to interlock with their respective back sections 120 b 122 b 124 b and door stop 300 see fig3 during installation if the thickness t of the building opening does not match the thickness t of the door frame 110 the installer may obtain a kit having substitute front sections 120 c 122 c 124 c to match the thickness t of the frame with the thickness t of the opening the installer may remove the front sections 120 a 122 a 124.