The DS is Dual Monitor Switch for Von Duprin 6000 series electric strikes.
DS option cannot be added to a Von Duprin 6000 series electric strikes in the field. It is only available factory inst...
Von Duprin 6223 electric strike is the most common closed back strike or the 6221 for open back strike on inactive leaf that can be used with Schlage L9000 or Von Duprin 7500 mortise lock.