Fail-Safe/Fail Secure, Body Only, 12/24VDC Electric Strike, Latchbolt Monitor, Oil Rubbed Bronze The 8500 series is a fire-rated, compact, high-performance electric strike featuring a unique concealed design for use with mortise locksets without a deadbolt. Designed for fast, convenient installation, the 8500 installs with little or no modification to the frame. Simply remove the existing strike plate, remove the dust box, and install it. Its strength is derived from a unique keeper pin locking design, enabling the 8500 to exceed Grade-1 ratings. This unique electric strike complies with NFPA 80-07 guidelines for retrofitting into fire-rated frames. The 8500 accommodates mortise latch bolts up to 3/4" throw. The high-performance 8500 Series is fire-rated, compact, and features a unique concealed design. The 8500 series is a unique electric strike that complies with NFPA 80-07 guidelines for retrofitting into fire-rated frames. The 8500 accommodates mortise latch bolts up to 3/4" throw.