The Schneider A3XL4LR is a 44mm illuminated mushroom head pushbutton in red, part of the Harmony A3 series. This is a panel-mount control station component — the 44mm diameter head provides a large, easy-to-actuate surface for emergency-stop or palm-actuation applications on machinery control panels.
The 44mm illuminated mushroom head in red is a standard form factor for emergency-stop actuators on industrial control stations. The illumination indicates the actuator's active or tripped state. Panel cutout and mounting follow the Harmony A3 series footprint, which is a common 22mm or 30mm mounting hole depending on the adapter — verify the base mounting dimensions against your existing enclosure before specifying.