The really sturdy one. This lightweight frame allows you to mount a GoPro 3 or GoPro 4 without its housing on the 9mm skid mount. As already mentioned, this is a VERY sturdy mount ... If you're into 3D cinematography just mount two of these on the same rod, an ideal interocular distance of 65mm (2.5in) is easily achieved using this mount.
Alternatively use it to mount a Gopro to a variety of RC controlled helicopters using one of the 9mm mount sets.