The unit is designed to prevent the recirculation or spread of smoke by air handling systems, fans, and blowers. Complete systems may be shut down in the event of smoke detection. It is designed and built to meet all local code requirements, as well as the NFPA and ICC standards regarding HVAC supply and return duct smoke detectors. Output terminals are provided for remote status indicators and test/reset key switches or push buttons.  The SL Series includes many features that represent true innovations from current generation duct smoke detectors. Our traditional installer/service-friendly approach has been closely followed and expanded throughout the SL Series design. Our attention to detail has yielded a host of “No-Tools Required” features to ease installation and service tasks.  Addressable detector heads are compatible with National’s Digicomm™ protocol. For non-addressable applications, see the Conventional SL Series bulletin.