This adapter works by clamping onto an eyepiece or eyepiece drawtube while holding a smaller point-and-shoot style digital camera on a movable platform. Below are measurements of the various spacings and adjustments possible with the adapter to help determine what size of camera will work with it.
Here is a diagram of the adapter:

The platform J measures approx 3” x 4” across its widest parts.
The clamp assembly determines how large an eyepiece or eyepiece drawtube the adapter can work with. The scope holding clamp C measures 1-1/8” deep. The clamp adjusting knob A moves the adjustable clamp plate B from a minimum opening of 1-1/8” to a maximum of 2-5/8” (it can adjust to clamp onto either 1/14” or 2” eyepieces/drawtubes, which is why it’s called a 2” adapter). Tripod socket G allows the adapter to be used with a tripod.
Camera depth accommodation is determined by the platform grooves K and the placement of H and I, the 1/4x20 camera mounting screw and its lock, the camera fixing screw. The space between the groove centerlines is 1-1/8”. The mounting screw can slide back to allow 2-1/2” maximum distance between the mounting screw and the scope holding clamp. This would be the maximum depth for a camera between its lens front and the position of its 1/4x20 tripod socket in the camera base. The minimum distance is 3/4”.
The horizontal fine-tuning knob D is not actually seen in the diagram. It adjusts the camera to the right and left by a range of 2-5/8” side to side.
The vertical fine-tuning knob F allows vertical adjustment of the camera of 1-5/8” up and down.