The SW181 series is specially designed for DC applications, in particular for switching electric motors on and off in heavier vehicles such as; industrial trucks, airport vehicles, forklift trucks, etc.
Extensions to the item codes can be:
B = with spark extinguishing magnets (blowout)
P = closed housing (protected)
L = large contact set (large)
po = long in (prolonged)
co = continuous operation (continuously)