Hi-Spec Mains Heat Detector with 9V Battery Backup The Inter connectable heat alarm form Hi-Spec is designed to detect a change of heat that will sound if one is detected. the device can be used in areas where smoke alarms are not possible to (garage, laundry room and attic) this device from hispec can be interconnected up to 40 of their heat and/or smoke alarms over 150m distance using the single white wire. This product comes with a unique first fix base which allows the installer to complete the wiring before plasterers and painters can coat the surface without interfering with the detectors circuitry Main Features: Test function 5 year guarantee Loud 85dB alarm Insect proof Technical Specification: Diameter: 113mm Width: 45mm Includes 5 Year Warranty