Mounting Of The Actuator To The Damper Axle Shaft Or Jackshaft Is Via A Cold-Weld Clamp. Teeth In The Clamp And V-Bolt Dig Into The Metal Of Both Solid And Hollow Shafts Maintaining A Perfect Connection. The Specially Designed Clamp Will Not Crush Hollow Shafts. The Bottom End Of The Actuator Is Held By An Anti-Rotation Strap Or By A Stud Provided By The Damper Manufacturer. The Actuator Is Mounted In Its Fail Safe Position With The Damper Blade(S) Closed. Upon Applying Power, The Actuator Drives The Damper To The Open Position. The Internal Spring Is Tensioned At The Same Time. If The Power Supply Is Interrupted, The Spring Moves The Damper Back To Its Fail-Safe Position. Made in United States. Manufactured by Belimo Air Controls.