Since buying my first dashcam, I've had it unplugged by different mechanic shops three times. I finally decided to get this case to prevent it from happening again after having strong suspicion that a dealer took my car on a joyride, but ending up with no way to prove it. The case fits the DR900X pretty well, though it doesn't fit as nicely as the original mount. As with most Blackvue products, it definitely should not be as pricey as it is. $50 for a bit of plastic and metal is crazy, but there really aren't many other options if you need to secure your camera.
As others have mentioned, it would also have been nice to have a small access hole to press the wifi button without removing the case. It's possible to get a small screwdriver in around the plugs to press it, but it takes a bit of patience sometimes. I'll probably end up just drilling a small hole myself.