This Harmony XB4 Integral LED comes with 12V AC/DC BA9s base. It is compatible with Harmony XB4 and XB5. It is easy to install into standard 22mm diameter control and signaling devices. The simple modular design makes it easy for non-professionals to maintain, modify and adjust machines after installation. It is designed to fit into standard 22mm control and signaling devices, ensuring compatibility when installing into existing machines. It has high brightness for easy identification of function and operating mode.