I just received this in the mail today. I bought it on Amazon.com for $13.95. It was simple and self explanatory to put together. I didn't have any trouble attaching it to my air vent. The phone fit with no problem at all and should hold the Droid X. I can measure the possible max width and edit this post later. The mount stays attached when the phone is in it. There is plenty of room to have the car charger plugged into the phone at the same time. I can also take pics later if anyone wants to see it.
Any other questions about it, feel free to ask.
Any other questions about it, feel free to ask.