1. Located at the end of the HRSG Main Stack 2. Pressure Relief - Pressure relieved by self-opening when high pressure is generated in HRSG 3. Rainproofing function - Drain rainwater infiltrated into the stack to protect equipment 4. 2 blades or 4 blades depending on size and application 5. Driving method : Electirc Actuator 6. Option : Brake Brake cylinder (hydraulic shock absorber) to protect workers around stack dampers 7. Patent: Self opening function