This article explains how to exchange your ZEMAX hardlock key for a new Sentinel USB key.  Follow these steps if you have a defective key, or if you need a USB key instead of a parallel port type.  (Note:  If you already have a Sentinel USB key and you think it might be defective, please see the Knowledge Base article "What to do when ZEMAX will not run".)

*PLEASE READ THIS ENTIRE ARTICLE CAREFULLY AND FOLLOW INSTRUCTIONS PRECISELY TO AVOID MISUNDERSTANDINGS AND EXPEDITE YOUR KEY EXCHANGE.*