Wafer Style Butterfly compact design low torque Butterfly Damper DKG, DKL, DKR (Please contact us for specific needs):Used to control the flow of gas and combustion air which burner needs;Wafer Style Butterfly, compact design and low torque;DKR is used for hot air and smoke with a medium temperature ranged from -20°C to 650°C; The Material of body and axle are heatresistant gray iron and ...