4-1393159-3 is a relay hold-down spring accessory specifically designed for use with the 27E166 screw terminal socket in Potter & Brumfield KHA relay systems. This spring component is manufactured by TE Connectivity and provides mechanical retention and stability for relays mounted in 27E166 sockets. The hold-down spring integrates with the socket assembly to ensure secure positioning and reliable electrical contact during operation. It is part of the comprehensive accessories portfolio for general-purpose and industrial relay applications, supporting various mounting configurations and installation methods. This accessory is essential for maintaining relay stability in industrial control systems and equipment requiring dependable relay retention.