Quanum DIY FPV Goggle V2, are very nice low cost PFV goggles, bu they have a big defct: it is impossible to focus, because the focal plane is about 9cm beyond the screen position ....
This adapter allows you to put the image in perfect focus.
The adapter is composed of a body and a frame, I've also included an half body in case you preferes to print it in two different moments (ex. the printer bed is smaller)
Good FPV flyes