adjacent the door opening in which the frame is installed at the upper corners of the frame the casing components of the jambs and header meet at a mitred corner 22 as illustrated most particularly in fig2 and 3 each of the frame elements that is each of the jambs and the header includes two components 24 and 26 the component 24 is an elongate sheet metal element with two right angle bends 28 and 30 adjacent one of its edges providing two flanges 32 and 34 and a door casing flange 36 which ends at a right angle bend 38 this provides a flange 40 extending part way across the inside face of a door opening and terminating in an outwardly directed lip 42 the component 26 is similarly shaped but includes an offset door stop section 44 in the form of a shallow channel into which the lip 42 projects as illustrated most particularly in fig3 an l shaped base clip 46 is spot welded to the flange 40 of each of the jamb components 24 and 26 the clip has two punched screw holes 48 when the frame is mounted in a door opening the base clips extend over the face of the drywall or other paneling 50 and are held in place with screws through the screw holes 48 into the stud as illustrated most particularly in fig4 the upper corners of the frame are held together with sheet metal corner clips 54 each clip is spot welded to a respective jamb component end engages the end of an associated header component through a slot 56 in the flange 34 of the header and a projection 58.