Performance complies with ANSI (American National Standards Institute) A156.5, Series 4000. UL (Underwriters' Laboratories) rated. 3 hour fire door. Door range: 1-3/8" - 2". Adjustable backset. 1-1/8" x 2-3/4" Square corner, T-strike. Door frame strike reinforcer with 3" screws. 7/8" wrought brass trim ring. Push-button locking. Can be opened from outside with small circular tool. Turning inside lever releases button.