BM17 XL 26D Arrow Mortise Lock The BM Series are engineered for strength and performance, and precisely manufactured to exact standards. Classroom Mortise Lock, X Lever, L Rose, Satin Chrome Arrow mortise locks are offered in a complete range of functions designed for commercial, institutional and industrial applications. They are engineered for strength and performance, and precisely manufactured to exacting standards. Arrow mortise locks are intended for heavy duty use in schools, hospitals and commercial buildings where security, durability and low maintenance are required. The lock case is made from heavy gauge steel, with zinc dichromate finish for corrosion resistance and it can be re-handed without disassembling the lock case. A wide selection of trim designs and functions are offered which meet or exceed the performance requirements of ANSI Grade 1.