[8881.00001] Truck (less Apron) - Ball Bearings

For manually operated or power operated sliding doors, weighing up to 2,500 lbs. Head Clearance: Distance top of door to bottom of track; minimum 4-1/2"", maximum 6-1/2"". Bottom of track to centerline of hole in sidewall bracket; 6-3/4" Construction: 3" diameter machined steel wheels. Frame, malleable iron.