FireKnight Photoelectric Smoke Alarm 9V Battery White This FireKnight Smoke Alarm is ideal in your space, adding a sense of safety to your area. It has an easy installation with fixings supplied, and a photoelectric sensor for detecting slow, smouldering fires. It has a 9V battery for long-term use. FireKnight Photoelectric Smoke Alarm Lithium Battery White This FireKnight Smoke Alarm is ideal in your space, adding a sense of safety to your area. It has an easy installation with fixings supplied, and a photoelectric sensor for detecting slow, smouldering fires. It has a long-life, 10 year lithium battery. Google Nest Protect - Wired This Google Nest Protect detects carbon monoxide (CO) and smoke from fast-burning as well as smouldering fires, and tells you where the danger is. You can use your phone to receive alerts and silence alarms, making it easy to keep track of what's happening in your home.* It is also compliant with Australian smoke alarm standards, tests itself automatically and has a long-lasting CO sensor that keeps working for up to 10 years.