The 4530 Standard Duty Deadlatch offers flexibility of traffic control during and after business hours. A reverse turn of the key while the bolt is held retracted retains the bolt to allow two-way traffic for hospitals banks stores and other buildings which require free entrance at certain times and exit-only at other times. 4530 Deadlatches are designed to fit without alteration the stile cutout for older MS1850 Deadlocks and discontinued 4250 Deadlatches of same backset. Turn key or operate handle...