Top hung on mounting brackets (not included) Adjustable mounting brackets (not included) 4-Wheel trolleys 7/8 inch nylon rollers Rides astride an upside down T-track design, also fits Grant 7000 series twin track systems Can be used on doors up to 1-3/4 inch thick and doors up to 100 lbs. May not work with your existing hanger set. Please see the following mounting brackets (Prime-Line parts N 7090 for pocket doors and N 6892 for rear bi-pass doors) Please refer to the line art drawing for dimensions and compare with your needs before ordering