Smoke detectors are used for the detection of smoke. Some are smoke/heat detectors, meaning that they contain both kinds of sensors in a single unit. These detectors can be hardwired or wireless. Please note that the placement and type of detectors is determined by the national fire code, and that your local fire dept has final say as to what they require and where. Please consult with your local fire dept and/or hire a professional installer if you are planning on putting fire protection devices on your security system.