The Siemens Building Technology GRD126.1U is a 24V, two-position spring-return damper actuator designed to control airflow in HVAC ventilation systems. It operates by converting electrical power into mechanical movement to open or close dampers, while its spring-return mechanism provides automatic positioning when power is interrupted. With a 30 lb-in torque rating, it delivers reliab... https://www.partshnc.com/grd1261u-siemens-building-technology-24v-2pos-sr-firesmk-actw2aux