1.25" Visual Back for the NexStar 4
The rear port of the NexStar 4 accommodates the same accessories as the Meade ETX-90/105/125. In the Additional Tips and Solutions chapter of my book, The NexStar User's Guide, I suggested a 1.25" visual back from Meade but apparently they are no longer offering this product.
CNC Parts Supply, Inc now offers a visual back for the NexStar 4 - http://www.cncsupplyinc.com/etxstuff.htm. Look for the "ETX Visual Back", item number ETXVB.