I've owned a few, and they are pressure fit using the original bezel gasket. They turn either direction and do not click, but are nice and snug. Loved having one on my old SKX171 PMMM mod, and have one on my current Vostok Amphibia. Murphy manufacturing makes a very nice product.According to the Murphy website, the bezel is not unidirectional / ratcheting.
I'm not sure what to make of that. Does the bezel still click and stay in place, but it'll just turn clockwise and counterclockwise?