Kidde 10y29 optical smoke alarm with built in 10 year battery kidde 10y29 this optical smoke alarm from kidde represents the cutting edge of alarms and has been been designed for easy installation while offering a guaranteed 10 years life no need to change batteries power source lasts units life span p equipped with a host of superb features including the optical photoelectric sensor which is highly efficient at detecting slow burning and smouldering fires such as furniture the smal