This appliance allows for reciprocal movement of both teeth to close the space between them. Elastics provide the force, while the bar, extending through the tube soldered to the molar band, keeps the teeth from tipping as movement occurs. Appropriately sized elastics are provided with each appliance and the patient should be instructed to change them daily. When you wish to eliminate the movement of one of the abutment teeth, using a jackscrew with labial/lingual arch wires, will provide the added anchorage needed to accomplish this. A small dab of premixed cold-cure acrylic may also be applied to the threads behind the second nut to further ensure force maintenance and prevent back-up. Note: A popular alternative to the jackscrew is the use of a nickel titanium coil spring activated by an adjustable Gurin Lock.