The Siemens 3SE3303-3B is part of the 3SE3 series of heavy-duty industrial limit switches. Here are some key points about it:

• Housing: Cast aluminum, suitable for extreme conditions.

• Contacts: Slow-action contacts with a "make before break" mechanism.
  

• Body Type: Available in wide housing with 3 conduit openings.

• Durability: Designed for industrial applications requiring high reliability.

• Replacement: The 3SE3 series is now obsolete, replaced by the 3SE2 series, which has different conduit sizes