Smatree Suction Cup Mount
It works okay. The two adjustment screws should be parallel instead of cross axis. Also, the upper one doesn't hold very well since there's isn't much grip for it to work with. The arm also suffers from twisting.
For static mounting, I'm sure it does a great job. For mounting on a car or other moving object, I would get the actual GoPro suction cup, and I did. It is worth the cost.