Camera Interface Adapters
So this is a question I get a lot. I come from the Film/Photography industry and standard mounting practice for the film/Photography industry is either a 1/4-20 or 3/8-16 threaded insert. This is why all small camera tripod mounts have a 1/4-20 interface. For some reason Gopro and Garmin decided not to follow this standard. The Drift, Sony and the newer contour cameras did and they have an integral 1/4-20 threaded insert in their body and an adapter is not required.
Another reason I decided to stray from the Gopro / Garmin standard is most of the off the shelf mounts only rotate in one axis and all aircraft lift struts are at an angle so its nearly impossible to get the shot angled how you need with the off the shelf GoPro or Garmin stock mounts. By incorporating a professional ball mount into the design, it also allows you to set the shot in an infinite of positions; forward, rearward, straight down, at the pilot, toward the wingtip and all things in between. Also by choosing to use a high quality professional ball mount it replaces all the plastic flimsy arms with a solid metal structure thus cutting down on camera vibration.
The ball mount has a cork washer that when the camera is installed it pre-loads the threads and adds enough friction that it will not vibrate loose from aircraft vibration or impact pressure from the wind. It actually takes a fair amount of torque to remove the camera once installed.