The Kidde safety alarm pack is a 5CO Carbon Monoxide Alarm and 29HD Optical Smoke Alarm in one pack. Power supply: 9V Alkaline Battery (Smoke Alarm) / 4 x AA Alkaline Batteries (CO Alarm). Sensor Technology: Smoke Alarm Certified by VDS to EN14604: 2005/ CE Certified CO Alarm Certified to BSI to EN50291: 2010/ CE Certified.