protrusion 61 and the proximal end of the respective projection members 55 57 for allowing the first shim member 49 to be snapped thereon to thereby secure the first shim member 49 to the door frame member 21 the first and second shim members 49 51 are identical to one another each shim member 49 51 has a substantially flat face 63 a first leg 65 at one end of the face 63 and a second leg 67 at the other end of the face 63 a v shaped projection 69 is located at each end of the face 63 sized and shaped identical to the v shaped protrusion 61 of the projection means of the door frame member 21 each leg 65 67 has an inwardly directed semispherical protrusion or rounded head 71 on the distal end thereof and an outwardly directed substantially semispherical groove 75 between the v shaped protrusion 69 and the rounded head 71 the v shaped protrusion 69 and semispherical groove 75 are identical in size and shape to the v shaped protrusion 61 and semispherical groove 62 while the semispherical protrusion 71 is a mirror image in size and shape to the semispherical grooves 62 75 to allow the first shim member 49 to be snapped fitted onto the door arm member 21 and to allow the second shim member 51 to be snapped fitted onto the first shim member 49 as clearly shown in fig4 and as will now be apparent to those skilled in the art the snap means of the.