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.