The A3XL4LM is a 44mm illuminated mushroom-head pushbutton with an amber lens, part of the A3 series of industrial pilot devices. The 44mm head diameter is the large-format size — typically specified for emergency-stop or prominent control stations where the actuator needs to be visually dominant and easy to strike in a panic. The amber illumination means the button glows when the integral lamp circuit is energized, giving a clear status indication on the panel face.
The 44mm mounting hole is the standard large cutout for this class of pilot device. Panel thickness and behind-panel depth must accommodate the lamp holder and contact block stack — typical for a mushroom-head actuator, the body extends further behind the panel than a flush pushbutton. Verify clearance behind the gland plate before committing the cutout.