I attached to NEX5 screen, it comes with two square metal frames (one spare),
which holds the viewer assembly with magnet, the viewer has a magnifier lens.
It is actually quite usable on NEX5 but no diopter adjustment unfortunately.
Although the viewer has long thread for you to adjust the lens with eye cup
assembly, so some adjustment will be easily done up to +2 far farsighted eyes.
I got it from "linkdelight.com", it took one month from Hong Kong to Canada!!
The package comes with > http://www.pbase.com/image/133739752/original