The Rockwood 585-24 Surface Slide Bolt is 24" Long, 26D - Satin Chrome Plated (626), UL listed for use on inactive leaf of a pair of 3-hour labeled fire doors, The 585-24 Is a Heavy Duty Surface Mounted That Includes a universal top strike and a mortise bottom strike, Rockwood 585-24 Also Locks in both the up and down position, In Addition Bolt locks automatically when thrown; can be released only by pressing knob toward door while retracting. 585-24 Can be used on any type of door And Accommodates a padlock.