The KEYMAN M700 Series Sectional Mortise Lock is an extra heavy-duty commercial model. Built with stainless steel bolts and high-strength steel alloy internal parts, it is UL-listed for 3-hour fire resistance and meets ANSI/BHMA A156.13 Grade 1 standards. With a 3-5/8" (92mm) center cylinder-to-spindle dimension, it enables easy retrofitting of most mortise locks with minimal door prep.