Plug-in: used with 8 pin octal sockets. Allows for easy replacement without having to remove any control wiring. Macromatic sockets can either be mounted on 35mm DIN track or to the panel with two screws. All Macromatic plug-in time delay relays are UL Listed for use in both United States and Canada (cULus) when used with the appropriate Macromatic socket as well as Component Recognized (cURus) using any recognized socket.