"GENERATION 4" SINGLE BOX RAIL BRACKET Use at 2 intervals to hang rail to building Use 3/8" x 2" lag screws (not included) Wall mount trolley rail bracket For doors weighing up to 400 lbs. when brackets are on 24" centers and up to 450 lbs. on 18" centers References National Mfg. No. 104-349 (Ace No. 58956) Zinc finish