This includes the two main parts of the adjustable arm, thumbscrew, plastic washer, and rubber washer for the Atlas Standard support.
This arm is the only difference between Atlas Standard and the Atlas Short or Atlas Tall. If you have a Short or Tall, you can purchase this arm to convert it to a Standard.
NOTE: The holes where the arm attaches to the magnet are not threaded. The screw will self-tap the hole and create the threads when inserted for the first time.