The Edwards EST SIGA-SDH is an upgraded version of the SIGA-DH smoke detector. While both detectors serve the same purpose of detecting smoke in a fire alarm system, the SIGA-SDH offers enhanced features and performance compared to its predecessor. These enhancements may include improved sensitivity, better reliability, and possibly additional functionalities such as advanced diagnostics or compatibility with newer communication protocols. Overall, upgrading to the SIGA-SDH ensures that your fire alarm system remains up-to-date with the latest technology and provides optimal protection against fire hazards.