
You can see one filter on the camera and another attached to default filter. I think it's just a protective glass, not UV (any references are welcome).
The problem is the thread is not as long, and plastic on the camera prevents it from being screwed fully. I can turn it only for about 100 degrees. But it feels tight enough and should hold. If not filters are cheap on ebay. This set of 4 filters was about $14. I think I'll keep UV always on by default.
BTW, as filters are screwed in the wrong way, you cannot rotate them. I.e. polarized wouldn't work unless you use two of them to get sort of adjustable ND filter. May need counter-balance on the back of the camera.