IEC 60947-1, EN 60947-1 IEC 60947-5-1, EN 60947-5-1. 22 mm Push Button Heads, Plastic. Siemens extremely rugged IP69K high-grade plastic push button heads. Avaliable in a variety of colours, illuminated, non-illuminated or mushroom style. Self-holding function of the actuator when mounting Twist prevention integrated into patented holder design Stackable contact modules Suitable for use in extreme environments No special tools required Simple geometry for mounting holes Latching or Momentary available