Set includes 8 knobs and 4 threads, which is enough for four doors. Each door requires two doorknobs (one for each side of the door) and one thread. To install, simply drill a hole to accommodate the diameter of the doorknob threaded screw. Screw one knob onto one end of a threaded screw. Insert the assembled doorknob with the screw through the door. While holding the unit in place screw on the remaining doorknob. Designed for use with one-inch (1:12) scale dollhouses or miniature doors.