A plurality of studs (14) are spaced apart relative to each other. Upper end portions (32) of the studs fit into an upper channel space (22) and lower end portions (34) fit into a lower channel space (30). The lower channel space (30) is defined in part by a pair of spaced apart sidewalls (24, 26). Screw fasteners (52) extend through the sidewalls (24, 26) and connect them to the lower end portion (34) of the stud (14). The studs (14) have upper ends that are spaced from a web (20) forming the upper boundary of the upper channel space (22). Vertical elongated slots (48, 50) are provided in the sidewalls (38, 40) of the studs (14). Screw fasteners extend through the sidewalls (16, 18) of the upper channel member (10) and then extend into and through the slots (48, 50). The heads of the screw fasteners (52) bear against the sidewalls (16, 18) when the screw fasteners (52) are tightened. This firmly connects the screw fasteners (52) to the sidewalls (16, 18), but there is no connection of the screw fasteners (52) to the upper end portions of the studs (14). When the screw fasteners (52) are tightened, there is no clamping action between the heads (54) of the screw fasteners (52) and the upper end portions (32) of the studs (14). As a result, the studs (14) are completely free to move up and down relative to the upper channel member (10), within limits established by the lengths of the slots (48, 50).