HMS-D SIEMENS Manual Pull Station Addressable Dual Action (Part# 500-033400)The Siemens intelligent manual fire alarm boxes (Models HMS S HMS SZ and HMS D HMS DZ) provide the most advanced method of address programming and supervision. Each Model HMS Series manual box achieves the state of an intelligent initiating device by incorporating custom microcomputer chip technology with sophisticated bi directional communication capabilities with the panel, which include Siemens Modular, as well as Siemens 50 point, 252 point and