The SKPSDA is a DUAL-ACTION PULL STATION, requiring two motions to activate the station. The SKPSSA is a SINGLE-ACTION PULL STATION, requiring only one motion to activate the station. Installer can open stations without causing an alarm condition too. And there are key-operated test and reset locks, using lock plate actuators. Keys also match compatible FACP locks. Other features include Braille text on station handle and rotary address switches for fast installation. UL listed.