IIRC, someone was asking about this lately. Thought I would pass it along.

Starting April 20, you will be able to trade in your Twenty 3G or Thirty 3G
headsets for the Zulu.

Part Number Description Your
Cost

TR0001 Trade-Up: Thirty 3G to Zulu $350.00

TR0005 Trade-Up: Twenty 3G to Zulu $450.00