This Harmony XB4 Integral LED is supplied with 24V AC/DC BA9s base and provides blue light.It is compatible with Harmony XB4 and XB5 illuminated push buttons.It is easily installed into a standard 22mm diameter controls and signalling units.Its simple modular design facilitates post installation servicing, modification and adaption of machines by non-specialists.It is designed to fit with a standard 22mm control and signaling units, ensuring compatibility when installing in pre-existing machinery.It features high brightness for easy identification of function and operation mode.