This Arrow D Series Deadbolt is designed for heavy duty commercial use, with an interchangeable core and single cylinder. The deadbolt is suitable for use with single cylinder doors, This product is a great choice for those looking for high quality commercial door hardware. Arrow D Series deadlocks are engineered to perform under the most extreme conditions where security is critical. Arrow Grade 1 extra heavy duty deadlock surpasses the demands of industrial, institutional and commercial applications. Two-piece housing with free-spinning outer ring to prevent wrenching.Solid steel deadbolt with hardened, free spinning steel pin and insert.