The BM11 BRL 4 Arrow Mortise Lock The BM Series are engineered for strength and performance, and precisely manufactured to exact standards. Apartment, Front Door Mortise Lock, BR Lever, L Rose, Satin Brass 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. The BM11 BRL 4 Arrow Mortise Lock 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.