Tyco SimplexGrinnell has a history of bringing quality and innovation to fire detection systems. In keeping with this tradition, we were the first to offer a UL-approved multi-sensor fire detector for detecting carbon monoxide (CO) concentrations. This important safety advancement is available to customers who use the Simplex 4100U/4100ES or 4010ES networked fire detection technology, including hospitals, college campuses, hotels, commercial complexes, correctional institutions and industrial facilities.